JPH10186374A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display device that is capable of obtaining stable operation even at a low temp., excellent in the display grade of a screen, and can realize bright color reproduction, by arranging supporting members so as to maintain the opening ratios of pixels in a part of the pixels of pixel groups. SOLUTION: Red resin layers 2a to 2f, green resin layers 3a to 3f and blue resin layers 4a to 4f formed by dispersing red, green and blue pigments into polyimide are formed at respectively different film thicknesses in correspondence to the pixels on a glass substrate formed with black matrices 1 and, simultaneously, columnar spaces 5a to 5i having the distances, defined as h, from the glass substrate 8 are formed on the black matrices 1 by a pigment dispersion method (etching method). The spacers 5a to 5i are formed at a ratio of one piece per 2 pixels. The columnar spaces 5a to 5i which are the supporting members are arranged at part of the pixels of the pixel groups in such a manner that the opening ratios of the pixels are maintained. Then, the generation of the air bubbles occurring in the shrinkage of the liquid crystals within liquid crystal cells, is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device for displaying an image on a screen composed of a pixel group in which a support member is arranged corresponding to some pixels.

[0002]

2. Description of the Related Art Conventionally, a group of pixels of a liquid crystal cell constituting a screen of a liquid crystal display device has, for example, as shown in FIG. The pixel is provided with the columnar spacer 30 formed as a unit.

In a liquid crystal cell constituting a liquid crystal display device, spacers for controlling the distance between the substrates are arranged in the gap between the substrates in order to maintain the quality of the display screen by controlling the thickness of the liquid crystal layer. I have. As the spacer, in addition to a spherical spacer using a spherical substance such as silica or polyethylene, a columnar spacer previously formed on a substrate in various patterning steps (Japanese Patent Application Laid-Open No. 59-139018 or Japanese Patent Application Laid-Open No. Hei 5-196946). In particular, in a liquid crystal cell to which a columnar spacer is applied, there is no light leakage due to abnormal liquid crystal alignment around the spherical spacer in a pixel portion, compared to a liquid crystal cell to which a spherical spacer is applied. Due to the advantages, the demand for columnar spacers is increasing. As shown in FIGS. 10 and 11, the columnar spacer 30 is usually provided on a light-shielding layer (black matrix) 31 provided on a glass substrate so as to correspond to the opening 29 at a ratio of one per pixel. Formed and arranged by patterning.

[0004] In a liquid crystal display device in which the display screen is colored, the pixel group is configured to transmit the three primary colors of light, red (R), green (G), and blue (B) alternately. , Pixels having the same aperture ratio.

[0005]

However, as described above, when a liquid crystal display device is constituted by a liquid crystal cell in which columnar spacers are formed and arranged at a ratio of one for each pixel, when used in a low temperature region, Since the density of the columnar spacers is high, bubbles are generated inside the liquid crystal cell due to the contraction of the liquid crystal, and there is a problem that the display quality of the screen is deteriorated.

Further, when a liquid crystal display device is constituted by a liquid crystal cell in which columnar spacers are formed and arranged at a rate of one for each pixel, the position of the region where the columnar spacers are arranged is increased as the aperture ratio of the pixels is increased. Since the size and the like of the columnar spacers are restricted and it is difficult to control the distance between the substrates, there is a problem that the display quality of the screen is deteriorated.

Further, in a liquid crystal display device including pixels having the same aperture ratio and having a screen for performing color display, it is difficult to control the R, G, and B luminous flux equally for each pixel. For this reason, there has been a problem that vivid color reproduction cannot be realized.

The present invention has been made in view of the above conventional example, and provides a liquid crystal display device capable of obtaining a stable operation even at a low temperature, having excellent display quality of a screen, and realizing vivid color reproduction. The purpose is to do.

[0009]

According to the present invention, there is provided a liquid crystal display device comprising: first and second substrates arranged so that main surfaces thereof face each other; and an electrode pattern formed on the first and second substrates. A liquid crystal layer held between the first and second substrates; and a support member disposed between the first and second substrates, for controlling a distance between the first and second substrates to be constant. A liquid crystal display device that drives a liquid crystal cell comprising the above-mentioned electrode pattern and displays an image on a screen composed of a group of pixels of the liquid crystal cell, wherein the support member has a part of pixels of the pixel group. Preferably, the arrangement is such that the aperture ratio of the pixel is maintained. ADVANTAGE OF THE INVENTION According to the liquid crystal display device of this invention, since a spacer is arrange | positioned at some pixels of the pixel group which comprises a screen, generation | occurrence | production of the bubble inside the liquid crystal cell due to the contraction of the liquid crystal can be prevented. Therefore, it is possible to stably operate even at a low temperature and to form a screen having excellent display quality.

[0010] In the present invention, the supporting member may be a first member.
There is no particular limitation as long as the distance between the second substrates can be controlled so as to be usually about 2 μm to 10 μm. For example, a resin-based spherical spacer such as a melamine resin, a urea resin or a polystyrene resin is used. Or a silica-based spherical spacer or the like, and furthermore, if the above-mentioned columnar spacer formed in advance on the substrate in various patterning steps is applied, compared with a liquid crystal display element using the spherical spacer, It is preferable to use a columnar spacer as the support member because there is an advantage that there is no light leakage due to abnormal liquid crystal alignment around the true spherical spacer in the pixel portion.

When a true spherical spacer is used as the support member, the spacer may be arranged in a gap between the first and second substrates by normal spraying so as to correspond to the pixels. When a columnar spacer is used, In order to effectively prevent the display quality from deteriorating, they are arranged on the substrate so as not to affect the aperture ratio of the pixels. Therefore, the spacers are formed and arranged on the black matrix formed on the substrate so as to correspond to the pixels, and from the viewpoint of preventing bubbles from being generated inside the liquid crystal cell at low temperature, two to three spacers are provided for every three pixels. It is desirable to arrange the pixels evenly at a rate of about one pixel. At this time, the mechanical strength of the liquid crystal cell is sufficiently exhibited. The shape of the columnar spacer is not limited as long as it is formed so as to control the distance between the first and second substrates to be constant. Usually, the columnar spacer is formed into a column, a rectangular parallelepiped, or a cube. The cross-sectional area of the cut surface obtained when cutting in a direction parallel to the main surface of the substrate is up to about 20 to
It is desirable that the thickness be about 500 μm ² .

Further, in forming the columnar spacers on the substrate in the patterning step, the step of forming the columnar spacers on the substrate may be provided independently, but from the viewpoint of suppressing an increase in the number of steps, For example, when forming a columnar spacer on a black matrix, it is desirable to perform the formation simultaneously with the formation of a red, blue or green colored resin layer typified by colored polyimide or the like on a substrate.

In the liquid crystal display device of the present invention, a pixel group forming a screen is formed by a first pixel providing a first aperture ratio and a second pixel providing a second aperture ratio different from the first aperture ratio.
Since the configuration of the first and second pixels can be made different from each other, the degree of freedom of the arrangement of the spacers is increased, and a screen excellent in display quality and color reproducibility is obtained. It becomes possible to configure.

At this time, the first aperture ratio given to the first pixel and the second aperture ratio given to the second pixel are:
It is appropriately selected according to the display quality required in the liquid crystal display device, and in consideration of the improvement of the brightness of the screen and the like, the first and the second are selected.
Although it is desirable to increase the aperture ratio as much as possible, in consideration of the arrangement of the columnar spacers and the like, usually, the first aperture ratio is selected to be about 90% to 55%, and the second aperture ratio is preferably about 88% to 50%. , The difference between the first aperture ratio and the second aperture ratio is 2
It is set within about 10%. Note that a pixel indicates a unit that forms and turns on a screen, and an aperture ratio indicates a ratio of an area of a portion through which light passes in one pixel.

The ratio of the first pixel providing the first aperture ratio to the second pixel providing the second aperture ratio is appropriately selected, and usually, the arrangement density in the pixel group is uniform. It is preferable to arrange them so that Further, the pixel group is not only composed of pixels giving two kinds of aperture ratios,
If necessary, it is also possible to use a pixel having three or more types of aperture ratios. In this case,
The abundance ratio of each pixel is preferably arranged such that the arrangement density in the pixel group is uniform.

In order to color the display screen, when forming R, G, and B colored resin layers typified by colored polyimide or the like corresponding to each pixel, each of the pixels has the same aperture ratio. By adjusting the layer thickness in the opening for each of R, G, and B, it is possible to make the luminous flux received from each pixel constant. However, in this case, in order to make the light flux constant, the colored resin layer must be formed based on the resin layer having the lowest light transmittance (B: blue resin layer). There is a limit. Therefore, the aperture ratio of each pixel is appropriately changed, and when the thicknesses of the R, G, and B resin layers are constant, the light transmittances of the pixels corresponding to R, G, and B are different for each of R, G, and B. Considering that, R,
In order to make the luminous flux received from each pixel corresponding to G and B constant, it is preferable to form R, G and B colored resin layers so as to correspond to each pixel having a different aperture ratio. Generally, the light transmittance in R, G and B is G
>R> B. Therefore, when the R, G, and B colored resin layers are formed in the order of B, R, and G so as to correspond to the pixels that provide a high aperture ratio, R, G, and The luminous flux of B can be maximized, and the screen can be further brightened. The luminous flux represents the brightness of light perceived by the naked eye, and when monochromatic light having an energy of 1 watt is sent out within a certain solid angle, the corresponding luminous flux is 650 lu at a wavelength of 555 nm.
Using spectral luminous efficiency was determined to be the (lumen) V _lambda is expressed as follows. That is, if the light is a continuous spectrum,

[0017]

(Equation 1) If the light represented by the formula (1) is incident on a certain solid angle, the luminous flux F corresponding thereto becomes

[0018]

(Equation 2) Where E _λ is the energy of light, λ _v and λ _r
Are the visible shortest wavelength 380 nm and the visible longest wavelength 7
70 nm.

The light transmittance is defined as the intensity of light after a light having a specific wavelength of intensity I ₀ is perpendicularly incident on a target surface and passes through the target with a thickness d having a smooth parallel plane. Is given by I / I ₀ when I becomes I (I = I
^{_{0 (1-R) 2 e}} -αd; α is the absorption coefficient of the target).

In the present invention, the first and second substrates are not limited as long as they are excellent in heat resistance and chemical resistance and can be applied to a liquid crystal cell. A glass substrate such as glass or quartz glass can be used. Further, the main surface refers to a surface on the side where the liquid crystal is sandwiched in the liquid crystal cell.

Further, in the present invention, the electrode pattern may be, for example, a transparent conductive layer formed for driving a liquid crystal cell, such as a scanning electrode and a signal electrode in a simple matrix driving system, and a pixel electrode in an active matrix driving system. A pattern made of a thin film (ITO: Indium Tin Oxide) can be given.

Further, in the present invention, the liquid crystal usually seals a sealing agent disposed so as to hold the liquid crystal in a gap between the first and second substrates and a liquid crystal injection port provided in the sealing agent. It is held in the gap between the first and second substrates using a sealant. The type of the sealant is not particularly limited as long as it is a sealant generally used for a liquid crystal display element. Examples of such a sealant include mainly a thermosetting resin and an ultraviolet curing resin, and the thermosetting resin may be a one-part type or a two-part type prepared before use. Usually used. As such a thermosetting resin, an epoxy resin or a phenol resin having a high degree of crosslinking can be suitably used, and as the curing agent,
Examples include amines, carboxylic acids and acid anhydrides.

Further, the sealing agent can reliably seal the sealing portion even under the condition that the sealing agent is in contact with the liquid crystal or the substrate and the sealing portion are wetted by the liquid crystal during sealing. Because of the necessity, a high-purity resin such as a silicone resin, an ultraviolet curable resin, an epoxy resin, or an acrylic resin can be suitably used as the sealant.

Note that the liquid crystal display device of the present invention can control the aperture ratio of a pixel regardless of a driving method such as a simple matrix type or an active matrix type.
It goes without saying that various types of liquid crystal display devices can be used.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display device of the present invention will be described in detail with reference to the drawings. In each of the drawings, the same components are denoted by the same reference numerals, and description thereof will be omitted. Example 1 First, as shown in FIG. 1, a red resin layer 2a in which red, green, and blue pigments are dispersed in polyimide on a 1.1-t thick glass substrate on which a black matrix 1 is formed.
To 2f, green resin layers 3a to 3f and blue resin layer 4a to
4f is different for each pixel and has a different layer thickness (1.5 μm).
m, 1.8 μm and 1.6 μm), and at the same time, columnar spacers 5 a to 5 i whose distance h from the glass substrate 8 was 5.0 μm were formed on the black matrix 1 by a pigment dispersion method (etching method). In FIG. 1, the aperture ratio of the pixels corresponding to the red resin layers 2a to 2f, the green resin layers 3a to 3f, and the blue resin layers 4a to 4f is 70.
%. The spacers 5a to 5i are formed at a rate of one per two pixels, and the maximum cross-sectional area obtained when the spacer is cut in a plane parallel to the glass substrate is 200.
μm ² .

Next, as shown in FIG. 2, a glass substrate 8 (substrate with a color filter) having a transparent electrode 7 formed on each pixel shown in FIG. An alignment film 11a and 11b made of polyimide is formed on a glass substrate 10 on which a transparent electrode 9 is formed, an alignment process is performed, and an injection port for injecting and discharging liquid crystal is provided. Two glass substrates 8 and 10 are bonded to each other, and a liquid crystal composition (E.M.
erck Co., Ltd .: ZLI-1132) and a torsion component (E. Merck Co., Ltd .: S-811) were sufficiently injected, and then a sealant (Sony Chemical Co., Ltd .: 8)
7A5), the inlet was sealed, and a 16-inch diagonal liquid crystal cell 12 was formed.

Next, as shown in FIG. 3, the liquid crystal display was constructed as follows. That is, the liquid crystal cell 12 and the backlight 13 are combined, and the flexible substrate 14 made of polyimide electrically connected to the liquid crystal cell 12 is bent toward the back side of the backlight 13. An integrated circuit group 15 for driving the liquid crystal cell 12 is mounted on the flexible substrate 14 by TAB (Tape Automated Bonding), and a printed circuit board 16 on which a wiring pattern for driving the liquid crystal cell 12 is formed is connected. When the flexible substrate 14 is bent to the back of the backlight 13, the integrated circuit group 15 and the printed circuit board 16 also move to the back of the backlight 13. The printed board 16 moved to the back side of the backlight 13 is fixed to the back face of the backlight 13, and the flexible board 17 electrically connected to the printed board 16 is connected to the liquid crystal cell 12 and The integrated circuit group 18 for driving the backlight 12 is mounted on a flexible substrate 19 bent on the back of the backlight 13.
Are connected via a connector (not shown) on the rear side of the device. Next, an insulating sheet 20 is arranged so as to cover the integrated circuit group 15, the printed board 16 and the flexible board 14.
Next, the spacer rubber 21 is arranged, and the liquid crystal cell 12, the backlight 13, and the bezel 22 are combined. Finally, the liquid crystal cell 12, the backlight 13, and the bezel 22
Are fixed by screws 23a to 23d to form a liquid crystal display device.

On the other hand, as a comparative example, a liquid crystal display device constructed in the same manner as in Example 1 except that a columnar spacer was arranged for each pixel was prepared.

When the obtained liquid crystal display devices were actually driven at a temperature below the freezing point, bubbles were generated in the above-mentioned conventional liquid crystal display device, and the image quality was remarkably reduced. In this case, the generation of bubbles was prevented, and no deterioration in image quality and color reproducibility was observed.

Example 2 As shown in FIGS. 4 and 5, the columnar spacers 5g to 5o having a distance h of 5.0 μm from the glass substrate 8 were dispersed at a rate of one per three pixels by the pigment dispersion method ( A liquid crystal display device was constructed in exactly the same manner as in Example 1 except that the liquid crystal display device was formed on the black matrix 1 by etching. That is, in FIG.
a to 2f, green resin layers 3a to 3f and blue resin layer 4a
The aperture ratio of the pixel corresponding to .about.4f is 70%, and the maximum cross-sectional area obtained when the spacers 5g to 5o are cut along a plane parallel to the glass substrate is 200 .mu.m.
m ² .

When each of the obtained liquid crystal display devices was actually driven at a temperature below freezing, bubbles were generated in the above-mentioned conventional liquid crystal display device, and the image quality was remarkably reduced. In this case, the generation of bubbles was prevented, and no deterioration in image quality and color reproducibility was observed.

In this embodiment, the ratio of the spacers arranged per pixel is lower than that in the first embodiment. However, no particular adverse effect is observed, and the quality of the image displayed on the screen and the quality of the image are reduced. The color reproducibility was comparable to that of Example 1.

(Embodiment 3) First, as shown in FIG. 6, a red resin in which red, green and blue pigments are dispersed in polyimide on a glass substrate having a thickness of 1.1 t on which a black matrix 1 is formed. Layers 24a to 24f, green resin layer 25
a to 25f and blue resin layers 26a to 26f are formed with the same layer thickness (1.6 μm ) corresponding to the pixels,
Spacer 27 whose distance h from glass substrate 8 is 5.0 μm
a to 27f and 28a to 28f were formed by a pigment dispersion method (etching method). In FIG. 4, the aperture ratios of the pixels corresponding to the red resin layers 24a to 24f, the green resin layers 25a to 25f, and the blue resin layers 26a to 26f are:
They are 70%, 70% and 75%, respectively.
Further, spacers 27a to 27f and 28a to 28f
Are formed at a rate of two per three pixels, and the maximum cross-sectional area obtained when cut along a plane parallel to the glass substrate is 200 μm ² each.

Next, as shown in FIG. 7, a glass substrate 8 (substrate with a color filter) having a transparent electrode 7 formed on each pixel shown in FIG. An alignment film 11a and 11b made of polyimide is formed on a glass substrate 10 on which a transparent electrode 9 is formed, an alignment process is performed, and an injection port for injecting and discharging liquid crystal is provided. Two glass substrates 8 and 10 are bonded to each other, and a liquid crystal composition (E.M.
erck Co., Ltd .: ZLI-1132) and a torsion component (E. Merck Co., Ltd .: S-811) were sufficiently injected, and then a sealant (Sony Chemical Co., Ltd .: 8)
7A5), the inlet was sealed, and a 16-inch diagonal liquid crystal cell 12 was formed. Then, a liquid crystal display device was constructed in exactly the same manner as in Example 1.

Then, when the obtained liquid crystal display device was actually driven, as compared with the above-described conventional liquid crystal display device in which the aperture ratios of all the pixels were equal and the spacers were arranged corresponding to each pixel, A screen with high contrast and improved image quality and color reproducibility was obtained.

When the liquid crystal display device was actually driven at a temperature below the freezing point, bubbles were generated in the above-described conventional liquid crystal display device, and the quality of the image was remarkably deteriorated. Was prevented, and no deterioration in image quality and color reproducibility was observed.

Further, in the liquid crystal display device of the present embodiment, the power consumption required for actual driving was equal to that of the above-described conventional liquid crystal display device, despite the brighter screen.

Example 4 As shown in FIGS. 8 and 9, red, green and blue pigments were dispersed in polyimide on a 1.1 t thick glass substrate on which a black matrix 1 was formed. Resin layers 24a to 24f, green resin layer 25
a to 25f and blue resin layers 26a to 26f are formed with the same layer thickness (1.6 μm) corresponding to the pixels,
Spacer 28 whose distance h from glass substrate 8 is 5.0 μm
A liquid crystal display device was constructed in exactly the same manner as in Example 3, except that a to 28f were formed at a rate of one per three pixels by a pigment dispersion method (etching method).

Then, when the obtained liquid crystal display device was actually driven, as compared with the above-mentioned conventional liquid crystal display device in which the aperture ratios of all the pixels were equal and the spacers were arranged corresponding to each pixel, A screen having high contrast and improved image quality and color reproducibility could be obtained. Even at a temperature below the freezing point, generation of bubbles was prevented, and no deterioration in image quality and color reproducibility was observed.

Further, in the liquid crystal display device of the present embodiment, the power consumption required for actual driving was equal to that of the above-mentioned conventional liquid crystal display device, even though the screen was brighter.

In this embodiment, the ratio of the spacers arranged per pixel is lower than that in the third embodiment. However, no particular adverse effect is observed, and the quality of the image displayed on the screen and The color reproducibility was comparable to that of Example 3.

[0042]

As described above in detail, according to the liquid crystal display device of the present invention, since the spacers are arranged in some of the pixels constituting the screen, the liquid crystal display device is exposed to a low-temperature environment or the like. Even if is shrunk, no bubble is generated inside the liquid crystal cell, and it is possible to provide a liquid crystal display device that can operate stably even at a low temperature.

Further, in the liquid crystal display device of the present invention, a pixel group forming a screen is formed by a first pixel providing a first aperture ratio and a second pixel providing a second aperture ratio different from the first aperture ratio.
Since the first and second pixels have different shapes of openings, the arrangement density of the spacers provided corresponding to the pixels can be appropriately adjusted, and the display quality of the screen is excellent. It is possible to provide a liquid crystal display device that realizes vivid color reproduction and can operate stably even at a low temperature.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a pixel group forming a screen of a liquid crystal display device according to a first embodiment.

FIG. 2 is a diagram schematically illustrating a cross section of a liquid crystal cell included in the liquid crystal display device according to the first embodiment.

FIG. 3 is a diagram schematically showing a configuration of a liquid crystal display device in Examples 1, 2, 3 and 4.

FIG. 4 is a diagram schematically illustrating a pixel group forming a screen of a liquid crystal display device according to a second embodiment.

FIG. 5 is a diagram schematically illustrating a cross section of a liquid crystal cell included in a liquid crystal display device according to a second embodiment.

FIG. 6 is a diagram schematically illustrating a pixel group forming a screen of a liquid crystal display device according to a third embodiment.

FIG. 7 is a diagram schematically illustrating a cross section of a liquid crystal cell included in a liquid crystal display device according to a third embodiment.

FIG. 8 is a diagram schematically illustrating a pixel group forming a screen of a liquid crystal display device according to a fourth embodiment.

FIG. 9 is a diagram schematically illustrating a cross section of a liquid crystal cell included in a liquid crystal display device according to a fourth embodiment.

FIG. 10 is a diagram schematically illustrating a pixel group forming a screen of a conventional liquid crystal display device.

FIG. 11 is a diagram schematically showing a cross section of a liquid crystal cell included in a conventional liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Black matrix 2a-2f ... Red resin layer 3a-3f ... Green resin layer 4a-4f ... Blue resin layer 5a-5o ... Spacer 6 ... Liquid crystal layer 7 ... Transparent electrode 8 ... Glass substrate 9 Transparent electrode 10 Glass substrate 11a, 11b Alignment film 12 Liquid crystal cell 13 Backlight 14
... Flexible board 15 ... Integrated circuit group 16 ... Printed board 17 ... Flexible board 18 ... Integrated circuit group 19 ... Flexible board 20 ... Insulating sheet 21 ... Spacer rubber 22 ... Bezel 23a
-23d Screws 24a-24f Red resin layer 25a-25f
Green resin layers 26a to 26f ... Blue resin layers 27a to 27f ...
Spacers 28a to 28f ... Spacers 29 ... Opening 3
0: columnar spacer 31: black matrix

Claims (3)

[Claims] 1. A first and a second substrate arranged so that main surfaces thereof face each other, an electrode pattern formed on the first and the second substrates, and a holding member between the first and the second substrates. A liquid crystal cell having a liquid crystal layer formed and a support member disposed between the first and second substrates and controlling the distance between the first and second substrates to be constant. A liquid crystal display device that displays an image on a screen configured by a pixel group of the liquid crystal cell, wherein the support member is arranged in some pixels of the pixel group so as to maintain an aperture ratio of the pixel. A liquid crystal display device characterized by the above-mentioned. 2. The method according to claim 1, wherein the pixel group includes a first pixel providing a first aperture ratio and a second pixel providing a second aperture ratio different from the first aperture ratio. The liquid crystal display device according to claim 1. 3. The liquid crystal cell according to claim 1, wherein, when an image is displayed on a screen of the liquid crystal cell, light beams received from the first pixel and the second pixel are equal.
3. The liquid crystal display device according to 1.