JPH06301020A - Display device - Google Patents

Abstract

PURPOSE:To lessen the reflection to a display screen. CONSTITUTION:An antireflection film 21 for decreasing reflected light by utilizing the interference of light is formed on the front surface F of a front surface polarizing filter layer 14 disposed on the front side of a display pixel layer 11 and a rough surface 22 for light scattering or an antireflection film consisting of fine ruggedness is formed on the rear surface F2 of a front surface transparent plate layer 13, by which the reflection of external light on the front side of the display pixel layer 11 is lessened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to a display device for visually recognizing light from a display pixel through a transparent plate layer such as glass or plastic.

[0002]

2. Description of the Related Art In a display device such as a liquid crystal display, a plasma display or an EL display, light from a displayed image is visually recognized through a transparent plate layer such as glass or plastic.

FIG. 6 shows an example of a conventional display device (conventional example 1).
Shows the basic structure of the liquid crystal display. In FIG. 6, 1 is a liquid crystal layer, 2a, 2b are electrodes, 3a, 3
b is a transparent plate layer, F ₁ is a front surface of the front transparent plate layer 3 a, F ₂ is a boundary surface between the front transparent plate layer 3 a and the front electrode 2 a, and F ₃ is a rear transparent plate layer 3 b and a rear electrode 2 b. The boundary surface, F ₄ is the rear surface of the rear transparent plate layer 3b, CV1 is the backside illumination light, and CV2 is the outside light.

As described above, when the transparent plate layers 3a and 3b are provided, when the external light CV2 is incident on the display device, the external light CV2 enters the display device.
V2 is each surface F ₁ , F ₂ , F ₃ , of the transparent plate layers 3 a, 3 b,
Reflect at F ₄ . Therefore, not only the light of the display image by the backside illumination light CV1 but also the reflected light CV3 by the transparent plate layers 3a and 3b is seen at the same time. That is, the reflection CV3 of the external light CV2 on the display screen occurs, and the display screen becomes difficult to see.

In order to solve this problem, conventionally, the front surface F ₁ of the front transparent plate layer 3a is subjected to a non-glare treatment 4 as shown in FIG. 7 (conventional example 2) or an antireflection film as shown in FIG. (Anti-reflection coating:
Forming 5 (abbreviated as AR coating) (conventional example 3)
Was.

Here, the non-glare treatment 4 refers to forming fine irregularities on the surfaces of the transparent plate layers 3a and 3b made of glass or plastic.

The AR coating 5 is a transparent plate layer 3a, 3b made of glass, plastic, or the like, and a thin film such as a dielectric is formed on the surface from which light is reflected. A coating that reduces reflection by transmitting through the surface and reflecting from the thin film-coated surface cancels each other by canceling interference.

[0008]

Prior art example 2 shown in FIG.
As described above, when the antiglare treatment 4 is performed on the front surface F ₁ of the front transparent plate layer 3a, all the reflected light CV3 by the external light CV2 is scattered, so that the brightness of the reflected light CV3 is reduced.
However, in this case, as shown in FIG. 9, since there is a distance between the liquid crystal layer 1 as the display image surface and the front surface F ₁ of the front transparent plate layer 3a, a virtual image is generated, and the image on the display screen is blurred. And the visibility of the display screen deteriorates.

When the AR coating 5 is applied as in the conventional example 3 shown in FIG. 8, the reflected light CV3a on the front surface F ₁ of the front transparent plate layer 3a is reduced by the effect of the AR coating 5, but other reflecting surfaces _{F 2, F 3,} reflected light CV3b at _{F 4,} CV3c, is CV3d exists. Of these, the reflected lights CV3c and CV3d on the reflecting surfaces F ₃ and F ₄
With respect to, the outside light CV2 to consider the transmittance of light to reach the reflection surface F _3, F _4, the influence is small. However, due to the influence of the reflected light CV3b on the reflection surface F _2, there is reflection of the display screen of the external light CV2, poor visibility.

An object of the present invention is to provide a display device capable of preventing glare on the display screen, keeping the image on the display screen clear, and improving the visibility.

[0011]

As shown in FIGS. 1 and 2, a display pixel layer 11 and a front electrode layer 12 disposed on the front side of the display pixel layer 11 are provided. A front transparent plate layer 13 disposed on the front side of the front electrode layer 12,
The front polarization filter layer 14 arranged on the front side of the front transparent plate layer 13, the rear surface electrode layer 15 arranged on the rear side of the display pixel layer 11, and the rear surface arranged on the rear side of the rear surface electrode layer 15. The transparent plate layer 16 and the rear surface polarization filter layer 17 disposed on the rear side of the rear surface transparent plate layer 16 are laminated to form the display pixel layer 1
The display image of No. 1 is displayed on each of the layers 12, 13, 14, 15, 1
In the display device viewed through 6 and 17, reflection reducing means for reducing the reflection of the external light CV2 on the front side of the display pixel layer 11 is provided, and the reflection reducing means utilizes reflected light to interfere with the reflected light. The antireflection film 21 (AR coating) for reducing and the rough surface 22 for light scattering (non-glare treated surface) having fine irregularities are provided.
Is formed on the front surface F ₁ of the front polarization filter layer 14,
The light scattering rough surface 22 is a rear surface F of the front transparent plate layer 13.
₂ is formed.

The means for solving the problems according to claim 2 of the present invention is a reflection reducing means for reducing the reflection of the external light CV2 on the front side of the display pixel layer 11, as the front surface F of the front polarization filter layer 14.
₁ and the rear surface F ₂ of the front transparent plate layer 13 are formed with antireflection films 21 and 23 (AR coating) that reduce reflected light by utilizing light interference.

[0013]

In the means for solving the problems according to the first aspect, part of the external light CV2 from the front is reflected by the front surface of the antireflection film 21. The other part of the light enters the antireflection film 21, is reflected by the front surface F ₁ of the front polarization filter layer 14, and is emitted forward from the antireflection film 21. At this time, first the antireflection film 2
The light reflected on the front surface of No. 1 and the light reflected on the front surface F ₁ of the front polarization filter layer 14 and emitted to the front interfere with each other and cancel each other. As a result, the external light CV2 of the display device is displayed.
The amount of light reflected by is reduced.

Further, the front surface F _{1 of} the front polarization filter layer 14
The light that is not reflected by the light enters the front transparent plate layer 13 as it is, and then reaches the surface F ₂ . At this time, since the rough surface 22 having fine irregularities is formed on the rear surface F ₂ , light is diffusely reflected and does not appear as reflected light as linear light. Therefore, it is possible to prevent the external light CV2 from being reflected on the display screen, which has been a problem in the conventional examples 1 to 3.

Since the distance between the rough surface 22 and the display pixel layer 11 as the display image surface is significantly shorter than that of the second conventional example, the display real image and the virtual image are different from those of the second conventional example. The distance can be reduced, and the degree of blurring can be reduced.

In the second aspect, the antireflection films 21 and 23 reduce reflection of the external light CV2 on the front side of the display pixel layer 11. Particularly, by forming the antireflection film 23 on the display image surface or the surface closest to the display image surface, the external light CV
The reflected light of 2 is reduced, and the reflection of external light CV2 on the display screen is suppressed.

[0017]

【Example】

(First Embodiment) As a first embodiment of the display device of the present invention,
A liquid crystal display will be described as an example. The display device of the present embodiment is of a backlight type in which an illumination device (not shown) is arranged on the back surface, and as shown in FIG.
1 (liquid crystal layer), a front electrode layer 12 arranged in front of the display pixel layer 11, a front transparent plate layer 13 arranged in front of the front electrode layer 12, and a front surface of the front transparent plate layer 13. The front polarizing filter layer 14, the rear electrode layer 15 disposed on the rear side of the display pixel layer 11, the rear transparent plate layer 16 disposed on the rear surface of the rear electrode layer 15, and the rear transparent layer. Board layer 16
And a rear surface polarization filter layer 17 disposed on the rear surface thereof.

The display pixel layer 11 is made of, for example, a thermonematic liquid crystal of twisted nematic mode, and its molecular arrangement has optical anisotropy which causes a twist phenomenon by an electric field or a magnetic field. The display pixel layer 1
The display image of No. 1 is illuminated from the back side and each of the layers 12, 1
It is displayed by the passing light CV1 which passes through 3, 14, 15, 16, and 17. The front surface and the rear surface of the display pixel layer 11 are
The display pixel layer 11 is hermetically sealed with an organic or inorganic alignment film (molecular aligning agent) 18, and a not-shown seal member (sealant) sandwiched between the front and rear alignment films 18 is used. To be sealed.

The two electrode layers 12 and 15 are generally made of tin oxide (SnO ₂ ) or indium oxide (In ₂ O ₃ ).
Etc. are used.

The transparent plate layers 13 and 16 serve as substrates for protecting the display pixel layer 11 and the alignment film 18 and coating the electrode layers 12 and 15, and are made of transparent glass or transparent plastic. .

Here, in general, when light is allowed to pass through the surface of transparent glass or transparent plastic, a certain degree of light reflection occurs due to the difference in refractive index. In the display device of the present embodiment, when the external light CV2 is reflected on the front side of the display pixel layer 11, the external light CV2 is reflected on the screen, making the screen difficult to see. Therefore, the display device of the present embodiment is provided with reflection reducing means for reducing the reflection of the external light CV2 on the front side of the display pixel layer 11. The reflection reducing means is an antireflection film 21 (A
R coating) and a light-scattering rough surface 22 (non-glare treated surface) having fine irregularities.

The antireflection film 21 is formed on the front surface (hereinafter referred to as a thin film coated surface) F ₁ of the front polarization filter layer 14,
This antireflection film 2 is a thin film formed by using a dielectric or the like.
Light reflected from the front surface of No. 1 and the thin film coated surface F that passes through the thin film
_The reflected light reflected by ₁ interferes with each other and cancels each other, thereby reducing the amount of reflected light. Therefore, the thickness t of the antireflection film 21 is set to be t = (2m + 1) λ / 2, where λ is the light wavelength and m is an arbitrary positive integer.

The rough surface 22 scatters transmitted light and reflected light, and is formed on the rear surface F ₂ of the front transparent plate layer 13.

The polarizing filter layers 14 and 17 are made of a common material such as polyvinyl alcohol (PVA) or polyvinylene transparent film having iodine adsorbed thereon.

In the display device having the above structure, both electrode layers 1
When a voltage is applied to some or all of 2, 15, the molecular arrangement of the display pixel layer 11 is affected by the electric field. Then, a twist phenomenon occurs, and a display image is formed. This display image is illuminated from the back surface to form the layers 12, 13,
With the passing light CV1 passing through 14, 15, 16, and 17,
Displayed on the front side.

By the way, from the front side of the display device, external light C
V2 is incident. This external light CV2 is applied to the thin film coated surface F.
_This corresponds to the antireflection film 21 of _{No. 1} . Then, a part thereof is reflected on the front surface of the antireflection film 21. In addition, other external light CV
2 is a thin film coated surface F after passing through the antireflection film 21.
Hit ₁ . Some of the light striking the film to be coated surface F ₁ is reflected by the thin film to be coated surface F _1, it is emitted from the front surface of the antireflection film 21 again. However, first, the antireflection film 21
Of the light reflected on the front surface of the thin film and the light reflected on the thin film coated surface F ₁ and emitted to the front interfere with each other to cancel each other.
This reduces the amount of light reflected by the external light CV2 of the display device. Further, the light not reflected by the thin film coated surface F ₁ enters the front transparent plate layer 13 as it is, and the rear surface F ₂
Reach

Since the rough surface 22 made of fine irregularities is formed on the rear surface F ₂ of the front transparent plate layer 13,
Light is diffusely reflected and does not appear as reflected light as straight light. Therefore, it is possible to prevent the external light CV2 from being reflected on the display screen, which has been a problem in the conventional examples 1 to 3.

Further, as shown in FIG. 2, the distance between the rough surface 22 and the display pixel layer 11 as the display image surface is significantly shorter than that of the conventional example 2 shown in FIG. The distance between the displayed real image and the virtual image can be made smaller than that in 2, and the degree of blurring can be suppressed to be small.

As described above, by performing the non-glare processing on the display image surface or a surface close to the display image surface, the display image is not blurred, the reflected light of the external light CV2 is reduced, and the external light CV2 is reduced.
By suppressing the reflection of V2 on the display screen, the visibility of the display screen can be improved.

(Second Embodiment) As shown in FIG. 3, the display device according to the second embodiment of the present invention has an external light C on the front side of the display pixel layer 11.
As reflection reducing means for reducing the reflection of V2, the antireflection films 21 and 23 for reducing the reflected light by utilizing the interference of light are formed on the front surface F ₁ of the front polarization filter layer 14 and the rear surface F ₂ of the front transparent plate layer 13. (AR coating) is formed. The antireflection films 21 and 23 are made of the same material as the antireflection film 21 described in the first embodiment. Other configurations are the same as those in the first embodiment.

In the display device having the above-mentioned structure, outside light CV2 from the front passes through the front surface F ₁ of the front polarization filter layer 14 and the rear surface F ₂ of the front transparent plate layer 13 at each surface F ₁ , F ₂ . Although a part is reflected, the reflected light becomes dark due to the interference, and the amount of reflected light by the external light CV2 is reduced. Then, the light passes through the display pixel layer 11 and is reflected by each of the front surface F ₃ and the rear surface F ₄ of the rear transparent plate layer 16.

However, considering the light transmittance of the display pixel layer 11, the front surface F ₃ and the rear surface F _{4 of the} rear transparent plate layer 16 are considered.
The amount of reflected light at is almost negligible. Therefore, it is possible to suppress the reflection of the external light CV2 on the display screen and realize a display screen having excellent visibility.

(Third Embodiment) In the first and second embodiments, the rough surface and the antireflection film are omitted for each of the front surface F ₃ and the rear surface F ₄ of the rear transparent plate layer 16. For example, as shown in FIG. 4A, by forming the antireflection film 24 on the front surface F ₃ and the rear surface F ₄ of the rear transparent plate layer 16, for example, the effect of further improving the image quality can be obtained.

Here, in FIG. 4A, the incident external light CV2 is incident on the antireflection film 21 and the front polarization filter layer 1.
4 and the front transparent plate layer 13 and then partially rough surface 2
The light is scattered and reflected at 2, but the rest goes to the rear as it is and passes through the display pixel layer 11. The transmitted light is the antireflection film 2
4 and the rear transparent plate layer 16 are entered. At this point, the light tries to be reflected by the boundary surface, but the antireflection film 24 can cancel the reflected light by utilizing the interference of the light and reduce the reflected light.

External light CV2 reaching the antireflection film 24
Since the light has already passed through the rough surface 22 and the display pixel layer 11, the amount of light has already been reduced, and therefore the antireflection effect is generally smaller than that of the antireflection film 21 on the front side. However, when the amount of the external light CV2 is extremely large, such as when the usage environment is bright, the entrance of the external light CV2 into the rear surface cannot be ignored, and therefore the antireflection of the antireflection film 24 is effective.

The present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made to the above embodiment within the scope of the present invention.

For example, in each of the above embodiments, the display pixel layer 1
Although a liquid crystal of twisted nematic mode was used as 1, a nematic liquid crystal of dynamic scattering (dynamic scattering: DS) mode, guest host (GH) mode, phase change (phase change: PC) mode was also used. , Cholesteric liquid crystal, or solvent-modified (lyotropic) liquid crystal. In this case, for example, in the case of DS mode, GH mode, PC mode, etc., the polarizing plate can be omitted.

In each of the above embodiments, the liquid crystal display has been described as an example, but other than that, the present invention can be applied to a plasma display, an EL display or the like. Here, when a light-emitting body or a reflector is used as the display pixel layer 11, as shown in FIGS. 5A and 5B, a member behind the display pixel layer 11, that is, the rear surface electrode layer in each of the above-described embodiments. 15,
All the members corresponding to the rear transparent plate layer 16 and the rear polarization filter layer 17 can be omitted. Note that FIG. 5A shows an example in which the antireflection film 21 is formed on the front surface F ₁ of the front polarization filter layer 14 and the light scattering rough surface 22 is formed on the rear surface F ₂ , and its action on the external light CV2. Is the same as in the first embodiment. Further, FIG. 5B shows the front polarization filter layer 14
On the front surface F ₁ and the rear surface F ₂ of the front transparent plate layer 13 of the antireflection films 21 and 23 for reducing reflected light by utilizing light interference.
Is an example in which the external light CV2 is acted on by
It is similar to the second embodiment.

Further, in the first and second embodiments, the rough surface 22 and the antireflection film 23 are directly formed on the rear surface F ₂ of the front transparent plate layer 13, but, for example, the electrode layer 15 is interposed. However, if they are slightly separated, they may be formed separately.

Furthermore, in the third embodiment, the rough surface 22 for light scattering was formed on the rear surface F ₂ of the front transparent plate layer 13, but as shown in FIG. Prevention film 2
3 may be formed. Of course, a rough surface may be formed instead of the antireflection film 24 in FIGS. 4 (A) and 4 (B).

Further, in the above embodiment, the antireflection film 21 is formed.
Was arranged on the front surface F ₁ of the front polarization filter layer 14,
It may be arranged directly on the front surface of the front transparent plate layer 13.

[0042]

As is apparent from the above description, according to the present invention, in the display device in which the display image of the display pixel layer is visually recognized through the front transparent plate layer, reflection of external light on the front side of the display pixel layer is reduced. As a reflection reducing means, an antireflection film that reduces reflected light by utilizing light interference is formed on the front surface of the front transparent plate layer, and for light scattering consisting of fine irregularities on the rear surface of the front transparent plate layer. Since a rough surface or an antireflection film similar to the front surface is formed, it is possible to reduce the reflected light due to external light on the front side of the display pixel layer, and to the display screen of external light which has been a problem in Conventional Examples 1 to 3. It is possible to suppress the reflection of. In particular, when the rear surface of the front transparent plate layer is a rough surface for light scattering, the distance between the displayed real image and the virtual image can be made smaller and the degree of blurring can be made smaller than in Conventional Example 2 in which the front surface is a rough surface for light scattering. Can be suppressed. From these, there is an excellent effect that a display device having excellent visibility can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a display device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a difference in distance between a display real image and a virtual image in the display device according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a display device according to a second embodiment of the present invention.

FIG. 4A is a sectional view showing an outline of a display device according to a third embodiment of the present invention, and FIG. 4B is a sectional view showing an outline of a display device according to another embodiment of the present invention.

5A is a cross-sectional view schematically showing a display device according to another embodiment of the present invention, and FIG. 5B is a cross-sectional view schematically showing a display device according to another embodiment of the present invention.

FIG. 6 is a diagram showing how external light is reflected on each surface in Conventional Example 1.

FIG. 7 is a diagram showing how external light is reflected on each surface in Conventional Example 2.

FIG. 8 is a diagram showing how external light is reflected on each surface in Conventional Example 3.

FIG. 9 is a diagram showing a difference in distance between a displayed real image and a virtual image in Conventional Example 2.

[Explanation of symbols]

 11 Display Pixel Layer 12 Front Electrode Layer 13 Front Transparent Plate Layer 14 Front Polarization Filter Layer 15 Rear Electrode Layer 16 Rear Transparent Plate Layer 17 Rear Polarization Filter Layer 18 Alignment Film 21 Antireflection Film 22 Rough Surface for Light Scattering 23, 24 Antireflection Membrane CV1 Light passing through CV2 Ambient light

Claims (2)

[Claims] 1. A display device in which a display pixel layer and a front transparent plate layer disposed on the front side of the display pixel layer are stacked, and a display image of the display pixel layer is visually recognized through the front transparent plate layer. A reflection reducing means for reducing reflection of external light on the front side of the pixel layer is provided, and the reflection reducing means is an antireflection film for reducing reflected light by utilizing light interference, and light scattering consisting of fine unevenness. Display device, wherein the antireflection film is formed on the front side of the front transparent plate layer, and the light scattering rough surface is formed on the rear side of the front transparent plate layer. . 2. A display device in which a display pixel layer and a front transparent plate layer disposed on the front side of the display pixel layer are laminated, and a display image of the display pixel layer is visually recognized through the front transparent plate layer. A reflection reducing means for reducing reflection of external light on the front side of the pixel layer is provided, and the reflection reducing means uses an antireflection film for reducing reflected light by utilizing light interference, and the antireflection film is A display device formed on both front and rear sides of a front transparent plate layer.