JPH09230324A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light shielding (like a black mask) function and to improve light utilization factor. SOLUTION: A 1st optical film 31 having wedged parts 31A and 31B equipped with a horizontal incident surface 31a, an inclined surface 31b inclined to the incident surface 31a by a specified angle and an exit surface 31c perpendicular to the incident surface 31a and a 2nd optical film 32 provided to cover the 1st optical film 31 in order to make a boundary between the inclined surface 31b of the 1st optical film 31 and the film 32 a total reflection surface are provided in a non-pixel areas on the lower surfaces of the color filter elements 23R and 23G of a common electrode panel. For example, light perpendicularly entering the non picture element area of the color filter element 23R on a left side is totally reflected on the boundary between the inclined surface 31b of the wedged part 31A and the 2nd optical film 32 thereunder and radiated to a pixel electrode arranged under the color filter element 23R on the left side after its optical path is changed to the left side by 45 deg..

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art Generally, in a liquid crystal display device, in order to improve the visibility of each pixel, a metal thin film or a black dye is formed in a non-pixel region corresponding to each of a plurality of pixel electrodes arranged in a matrix. The structure is such that a light-shielding film (black mask) made of a content agent or the like is provided.

[0003]

However, in such a conventional liquid crystal display device, since the light-shielding film literally shields the incident light, there is a problem that the light utilization rate is poor. An object of the present invention is to have a light-shielding (black mask-like) function and to improve the light utilization rate.

[0004]

The present invention provides a liquid crystal display device in which liquid crystal is sealed between a pixel electrode panel having a plurality of pixel electrodes arranged in a matrix and a common electrode panel having a common electrode. In the non-pixel area corresponding to each of the plurality of pixel electrodes of the common electrode panel, an optical path changing means for changing an optical path of light incident on the non-pixel area to the pixel electrode side in the vicinity thereof is provided. is there.

According to the present invention, the optical path of the light incident on the non-pixel area of the common electrode panel is changed to the pixel electrode side in the vicinity by the optical path changing means, so that the non-pixel area of the pixel electrode panel is changed. Not only can the light be prevented from being emitted, but the light incident on the non-pixel area of the common electrode panel can be irradiated to the pixel electrodes in the vicinity thereof, and thus it has a light-shielding (black mask-like) function. The light utilization rate can be improved.

[0006]

1 (A) and 1 (B) show the essential parts of a liquid crystal display device according to an embodiment of the present invention. However, FIG. 1 (A) shows a plan view of the pixel electrode panel 1 of this liquid crystal display device in which the uppermost alignment film 15 is omitted. This liquid crystal display device has a structure in which the pixel electrode panel 1 and the common electrode panel 2 are bonded to each other via a sealing material (not shown), and the liquid crystal 3 is sealed between them.

The pixel electrode panel 1 has a structure in which gate lines 5 and drain lines 6 are provided in a matrix on a transparent substrate 4 made of glass, resin or the like, and thin film transistors 7 and pixel electrodes 8 are provided near each intersection. Has become. That is, the gate line 5 including the gate electrode 9 is formed at a predetermined position on the upper surface of the transparent substrate 4, and the gate insulating film 10 is formed on the entire upper surface thereof. A semiconductor thin film 11 made of amorphous silicon is formed at a predetermined position on the upper surface of the gate insulating film 10, and a channel protective film 12 is formed at the center of the upper surface of the semiconductor thin film 11. In this case, the semiconductor thin films 11 on both sides of the channel protective film 12 are made into n-type impurity implantation regions by implanting n-type impurities. A drain electrode 13 and a source electrode 14 are formed on the respective upper surfaces of these n-type impurity implantation regions, and a drain line 6 is formed at the same time when these electrodes 13 and 14 are formed. The pixel electrode 8 is formed at a predetermined position on the upper surface of the gate insulating film 10 so as to be connected to the source electrode 14. An insulating film 15 made of silicon nitride is formed on the thin film transistor 7, and an alignment film 16 is formed on the entire upper surface. A polarizing plate 17 is attached to the lower surface of the transparent substrate 4.

The common electrode panel 2 has a transparent substrate 21 made of glass or resin. The common electrode 22 is provided on the lower surface of the transparent substrate 21, and R is provided for each pixel on the lower surface.
(Red), G (green), B (blue) color filter elements 23
R, 23G, and 23B are provided. A non-pixel region on the lower surface of the color filter elements 23R, 23G, and 23B (that is, a non-pixel region corresponding to each of the plurality of pixel electrodes 8, that is, a gate line 5, a drain line 6, a thin film transistor 7, and their vicinity) Non-pixel area)
Is provided with an optical path changing film 24, which will be described later in detail. An alignment film 25 is provided on the entire lower surface. Also,
A polarizing plate 26 is attached to the upper surface of the transparent substrate 21. Although not shown, a backlight is arranged above the polarizing plate 26.

Next, the optical path changing film 24 will be described with reference to FIGS. 2 and 3. First, as shown in FIG. 2, the optical path changing film 24 includes the color filter elements 23R and 2R.
3G, 23B filter surface (that is, the common electrode panel 2
A wedge surface having an incident surface 31a parallel to the panel surface or the transparent substrate 21), an inclined surface 31b inclined at a predetermined angle with respect to the incident surface 31a, and an emission surface 31c perpendicular to the incident surface 31a. First having parts 31A, 31B
The optical film 31 and the wedge portions 31A and 31 of the first optical film 31.
To make the interface with the inclined surface 31b of B a total reflection surface, the first
The second optical film 32 is provided so as to cover the optical film 31. The first optical film 31 is, as shown in FIG.
Each of the color filter elements 23R, 23G, and 23B includes a plurality of linear wedge portions 31A and 31B arranged on both sides of each boundary surface without a gap. in this case,
The wedge portions 31A and 31B are basically the same as the gate line 5 and the drain line 6 shown in FIG.
They are arranged in a matrix. In addition, as shown in FIG. 2, two adjacent color filter elements 23R, 23R
The inclined surface 31b of the wedge portion 31A disposed on the left side of the G boundary surface faces the right side, and the wedge portion 31B disposed on the right side.
The sloping surface 31b faces to the left.

Here, when the cell gap is 10 μm and the width of the optical path changing film 24 in the portion corresponding to the gate line 5 and the drain line 6 is also 10 μm, the incident surface 31a of the first optical film 31 (that is, the common electrode). When the optical path of the light vertically incident on the non-pixel region of the transparent substrate 21 of the panel 2 is changed by, for example, 45 °, the light vertically incident on the non-pixel region of the transparent substrate 21 of the common electrode panel 2 is changed to a pixel electrode in the vicinity thereof. 8 can be irradiated, and the transmitted light from the pixel electrode 8 can be sufficiently increased. Therefore, in order to change the optical path of light whose traveling direction is parallel to the normal line direction of the incident surface 31a of the first optical film 31 by 45 °, the angle formed by the incident surface 31a and the inclined surface 31b is set to 67.5 °. .

On the other hand, the condition for making the interface between the inclined surface 31b of the first optical film 31 and the second optical film 32 a total reflection surface is that the refractive index of the first optical film 31 is n ₁ Membrane 32
When the refractive index of n is n ₂ and the critical incident angle for causing total reflection is θc, the following expression (1) may be satisfied. However, the incident angle is an angle formed by the incident light ray with the normal line of the inclined surface 31 b of the first optical film 31. sin θc = n ₂ / n ₁ (1)

By the way, as described above, the first optical film 3
The angle formed by the incident surface 31a of No. 1 and the inclined surface 31b is 67.
The critical incident angle θc for causing total reflection is 67.5.
If (°), then (n ₂ / n ₁ ) is approximately 0.94 from equation (1).
It becomes 2. On the other hand, it is desirable that the refractive index of the second optical film 32 does not differ greatly from that of the liquid crystal 3. For example, a nematic liquid crystal has a refractive index of 1.5.
Since it is about 1.9, the refractive index of the second optical film 32 is set to about 1.8. Then, the refractive index of the first optical film 31 may be about 1.95.

Next, an example of the material of the first and second optical films 31 and 32 and a method of forming the same will be described. In the case of a hydrogenated nitride film formed by plasma CVD, there is a correlation between the amount of contained hydrogen and the refractive index, as shown in FIG.
When the hydrogen content is about 22%, the refractive index is about 1.95, and when the hydrogen content is about 35%, the refractive index is 1.95.
It will be about 8.

Therefore, the film forming conditions by the plasma CVD are as follows: substrate temperature 250 ° C., silane (SiH ₄ ) gas flow rate 3
0 sccm, ammonia (NH ₃ ) gas flow rate 60 sccc
m, hydrogen (H ₂ ) gas flow rate 120 sccm, power 35
When it is set to 0 to 450 W, a hydrogenated nitride film having a refractive index of about 1.95 is formed with a hydrogen content of about 22%. Then, after a predetermined photolithography process which will be described later, the first optical film 31 having the wedge portions 31A and 31B is formed. Next, assuming that the film formation conditions by plasma CVD are a substrate temperature of 250 ° C., a silane gas flow rate of 20 sccm, an ammonia gas flow rate of 70 sccm, and a power of 350 to 450 W, a hydrogenated nitride film having a hydrogen content of about 35% and a refractive index of about 1.8. The second optical film 32 of is formed. In this case, the composition ratio of Si and N has little influence on the refractive index.

Next, a method of forming the first optical film 31 having the wedge portions 31A and 31B will be described with reference to FIG. First, as shown in FIG. 5A, the hydrogenated nitride film 41 is formed on the entire upper surface of the color filter elements 23R, 23G, and 23B (however, in FIG. 1B, the entire lower surface) under the above-described film forming conditions. The film is formed to a film thickness of about 1 μm. Next, a predetermined first resist pattern 42 is formed on the upper surface of the hydrogenated nitride film 41.
To form Next, using the first resist pattern 42 as a mask, BHF (buffer hydrofluoric acid, NH ₄ F: HF: H ₂ O =
When wet etching according to 1: 4: 5) is performed, as shown in FIG.
As shown in (B), a plurality of cross-section isosceles triangular portions 43
Are formed without gaps. In this case, the wedge parts 31A, 3
The angle of the inclined surface 31b with respect to the incident surface 31a of 1B depends on the advancing speed of the etching solution, and therefore on the adhesion between the resist pattern used for etching and the hydrogenated nitride film. Therefore, it should be controlled by the resist baking temperature. You can That is, in order to increase the angle of the inclined surface 31b with respect to the incident surface 31a of the wedge portions 31A and 31B, the baking temperature is increased to improve the adhesion, and to decrease the angle, the adhesion is decreased. It is only necessary to set the bake temperature to a low value, whereby the inclination angle of the inclined surface of the isosceles triangular section 43 can be arbitrarily selected. In this way, the isosceles triangular section 4
The apex angle of 3 is 45 °. After that, the first resist pattern 42 is removed.

Next, as shown in FIG. 5C, a predetermined half of each of the plurality of isosceles triangular portions 43 in cross section is covered.
A second resist pattern 44 is formed. That is, of the two adjacent color filter elements 23R and 23G, the second resist pattern 44 is formed on the inclined surface on the right side of the isosceles triangular section 43 on the left side of the color filter element 23R on the left side, and the color filter on the right side is formed. A second resist pattern 44 is formed on the inclined surface on the left side of the isosceles triangular section 43 on the element 23G. Next, when ECR dry etching is performed using the second resist pattern 44 as a mask, each predetermined half of the plurality of isosceles triangular portions 43 in cross section is removed, and as shown in FIG. Wedges 31A having an apex angle of 22.5 ° are formed on the color filter element 23R of the right side in a scattered manner, and on the color filter element 23G of the right side, an apex angle of 22. 5 ° wedge portions 31B are formed in a scattered manner. Next, the second of the wedge portions 31A and 31B
A water repellent treatment is applied to the vertical surface not covered with the resist pattern 44 in order to prevent the vertical surface from being corroded by wet etching in a later step. Next, the water repellent attached to the upper surfaces of the color filter elements 23R, 23G, and 23B is removed by dry etching.

Next, as shown in FIG. 5E, the hydrogenated nitride film 45 is again formed to a film thickness of about 1 μm on the entire upper surface under the above-described film forming conditions while leaving the second resist pattern 44. To film. Next, a predetermined third resist pattern 46 is formed on the upper surface of the hydrogenated nitride film 45. Next, when wet etching with BHF is performed using the 31st resist pattern 46 as a mask, the hydrogenated nitride film 45 interposed between the wedge portion 31A and the second resist pattern 44 is formed as shown in FIG.
By removing the upper side of the inclined surface shown by the dotted line in (E), the wedge portion 31A and the second resist pattern 44 are removed.
A wedge portion 31A having the same shape is formed between and (see FIG. 2).
reference). Further, the hydrogenated nitride film 45 interposed between the wedge portion 31B and the second resist pattern 44 is shown in FIG.
By removing the upper side of the inclined surface indicated by the dotted line, the wedge portion 31B having the same shape is formed between the wedge portion 31B and the second resist pattern 44 (see FIG. 2). After that, when the third resist pattern 46 and the second resist pattern 44 are peeled off, as shown in FIG.
The first optical film 31 having the wedge portions 31A and 31B is formed.

Next, the optical path changing film 24 of this liquid crystal display device.
The action of will be described with reference to FIG. The incident surface 31a is formed in the non-pixel area of the left color filter element 23R.
The light incident parallel to the normal direction of is totally reflected at the interface between the inclined surface 31b of the wedge portion 31A therebelow and the second optical film 32, and its optical path is changed to 45 ° to the left, and the exit surface is changed. The pixel electrode 8 arranged below the left side color filter element 23R is irradiated with the light passing through 31c, the second optical film 32, and the like. On the other hand, the light incident on the non-pixel region of the right color filter element 23G in parallel to the normal direction of the incident surface 31a is totally at the interface between the inclined surface 31b of the wedge portion 31B below and the second optical film 32. It is reflected and its optical path is turned to the right 45
The angle is changed, the light passes through the emission surface 31c, the second optical film 32, etc., and is irradiated to the pixel electrode 8 arranged below the right color filter element 23G.

As described above, in this liquid crystal display device, the optical path of the light incident on the non-pixel regions of the color filter elements 23R, 23G, and 23B (that is, the non-pixel regions corresponding to each of the plurality of pixel electrodes 8) is changed. Since the light path changing film 24 uniformly changes the pixel electrode 8 side in the vicinity thereof, light is prevented from being emitted from the non-pixel region corresponding to each of the plurality of pixel electrodes 8 of the pixel electrode panel 1. Not only is it possible to irradiate the pixel electrodes 8 in the vicinity thereof with the light incident on the non-pixel regions of the color filter elements 23R, 23G, and 23B of the common electrode panel 2; In addition, the color balance and the light utilization rate can be improved. Further, the light vertically incident on the non-pixel regions of the color filter elements 23R, 23G, and 23B has its optical path changed by 45 ° by the optical path changing film 24 and is applied to the pixel electrode 8 in the vicinity thereof, so that the viewing angle is improved. You can also plan. The second optical film 32 may be provided only in the non-pixel region or may be provided entirely.

By the way, when this liquid crystal display device is used as a reflection type, the region corresponding to the gate line 5 and the drain line 6, that is, the color filter element 23.
Since the optical path of the light incident on the non-pixel regions of R, 23G, and 23B is changed to the pixel electrode 8 side in the vicinity by the optical path changing film 24, the amount of light irradiated to the gate line 5 and the drain line 6 is considerably large. Therefore, the amount of light reflected and emitted from the gate line 5 and the drain line 6 can be considerably reduced. Further, the present invention is not limited to the reflection type liquid crystal display device and may be applied to a transmission type liquid crystal display device using a backlight. In this case, the light path changing film 24 is provided on the backlight side substrate and the color filter is provided on the viewing side substrate. It should be provided. The liquid crystal projector having such a structure is particularly effective because the backlight has a large amount of light.

In the above embodiment, the first optical film 31
Although the case where the wedge portions 31A and 31B are linearly arranged along the gate line 5 and the drain line 6 has been described, the present invention is not limited to this and, for example, as in another embodiment shown in FIG. The wedge portion 31C may be annularly arranged in the non-pixel region around the pixel region 51. In this case, if the inclined surface of the wedge portion 31C is on the outer side and the emission surface is on the inner side, all the light incident on the non-pixel area around the pixel area 51 is applied to the pixel electrode corresponding to the same pixel area 51. It will be. Although not shown, the second optical film may be provided only in the non-pixel region or may be provided over the entire surface in this case as well.

In the above embodiment, the optical path changing film 24 is used.
Has been described with respect to the case where the first optical film 31 having the wedge portions 31A and 31B (or 31C) and the second optical film 32 covering the first optical film 31 are formed.
It is not limited to this. For example, the wedge portion 31
First optical film 31 having A, 31B (or 31C)
And a reflective film made of an aluminum film or the like provided on the inclined surface of the first optical film 31.

Further, in the above embodiment, the case where no light-shielding film is provided has been described, but in order to prevent light from surely entering the semiconductor thin film 11 of the thin film transistor 7, the portion of the semiconductor thin film 11 is black pigment. It may be covered with a light-shielding film made of a content agent or the like, or a light-shielding film made of a metal thin film or the like may be provided on the common electrode panel 2 in a portion corresponding to the semiconductor thin film 11.

[0024]

As described above, according to the present invention, the optical path of the light incident on the non-pixel area of the common electrode panel is changed to the pixel electrode side in the vicinity by the optical path changing means. Not only can the light not be emitted from the non-pixel area of the pixel electrode panel, but also the light incident on the non-pixel area of the common electrode panel can be irradiated to the pixel electrodes in the vicinity thereof, and thus the light shielding (black In addition to having a (mask-like) function, it is possible to improve the light utilization rate.

[Brief description of drawings]

FIG. 1A is a plan view of a main part of a liquid crystal display device according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along the line BB.

FIG. 2 is a sectional view of a part of a color filter element and a light path changing film.

FIG. 3 is a perspective view of a portion of a color filter element and a first optical film.

FIG. 4 is a diagram showing the relationship between the amount of hydrogen contained in a hydrogenated nitride film formed by plasma CVD and the refractive index.

5A to 5E are cross-sectional views showing respective steps of forming the first optical film.

FIG. 6 is a schematic perspective view of a part of a color filter element and a first optical film according to another embodiment of the present invention as viewed from the lower surface side.

[Explanation of symbols]

 1 Pixel electrode panel 2 Common electrode panel 3 Liquid crystal 8 Pixel electrode 22 Common electrode 23R, 23G, 23B Color filter element 24 Optical path changing film 31 First optical film 31A, 31B Wedge portion 31a Incident surface 31b Inclined surface 31c Emission surface 32 Second Optical film

Claims (5)

[Claims] 1. A liquid crystal display device in which liquid crystal is sealed between a pixel electrode panel having a plurality of pixel electrodes arranged in a matrix and a common electrode panel having a common electrode, wherein the plurality of common electrode panels are provided. 2. A liquid crystal display device, wherein an optical path changing means for changing an optical path of light incident on the non-pixel area to the pixel electrode side in the vicinity is provided in a corresponding non-pixel area between the pixel electrodes. 2. The invention according to claim 1, wherein the optical path changing means includes an incident surface parallel to a panel surface of the common electrode panel, an inclined surface inclined at a predetermined angle with respect to the incident surface, and the incident surface. A first optical film having a wedge portion having an emission surface perpendicular to the first optical film, and the first optical film for making an interface between the inclined surface of the wedge portion of the first optical film a total reflection surface. Consisting of a second optical film provided so as to cover the light incident on the incident surface of the wedge portion is totally reflected at the interface with the second optical film of the inclined surface of the wedge portion,
A liquid crystal display device, wherein an optical path of the incident light is changed to the pixel electrode side in the vicinity thereof. 3. The invention according to claim 2, wherein the first
A liquid crystal display device, wherein the wedge portion of the optical film is linearly arranged in a non-pixel region. 4. The invention according to claim 2 or 3,
The liquid crystal display device according to claim 1, wherein the first and second optical films are formed of hydronitride films having different hydrogen contents. 5. The invention according to claim 1, wherein the optical path changing means includes an incident surface parallel to a panel surface of the common electrode panel, an inclined surface inclined at a predetermined angle with respect to the incident surface, and the incident surface. An optical film having a wedge portion having an emission surface perpendicular to the optical film, and a reflection film provided on the inclined surface of the wedge portion of the optical film, and incident on the incident surface of the wedge portion. A liquid crystal display device, characterized in that light is reflected by the reflection film to change the optical path of the incident light to the pixel electrode side in the vicinity thereof.