JPH06160830A - Display device - Google Patents

Abstract

PURPOSE:To provide a display device provided with a high contrast ratio in which the display of each pixel can be prevented from being affected by scattered light from the light scattering layer of a pixel neighboring the pixel. CONSTITUTION:This device is the one equipped with an insulating substrate 5 arranged at a light incident side and on the light emission side of which an electrode is formed, an insulating layer 1 consisting of three insulating layers 2, 3, and 4 arranged at the light emission side and on the light incident side of which the electrodes are formed, the light scattering layer 6 filled in the gap of the insulating substrate 5 and the insulating layer 1 and whose degree of scattering is controlled by applying a voltage to the electrodes at both sides, and light cutting off films 7, 8, 9, and 10 formed at the outermost plane of the insulating film 1 and a boundary planes between the layers 2, 3, and 4 and provided with light transmission parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device using a light scattering element.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a matrix type display device using a conventional light scattering element. This display device
Insulating substrate 101 on the light emitting side and insulating substrate 1 on the light incident side
The light scattering layer 103 is filled in a gap between the light scattering layer 102 and the light receiving layer 02. On one or both of the insulating substrates 101 and 102, the light-scattering layer 1 of the pixels 105 formed in a matrix is formed.
03 is provided with a means for applying a voltage. When a voltage is applied to this, the light-scattering layer 103 displays white, black, or an intermediate brightness depending on the difference in the scattering degree of the emitted light with respect to the incident light. A non-display portion 106 to which a voltage is not applied to the light scattering layer 103 is provided between the picture elements 105.

FIG. 5 shows a state of light emitted from the light scattering layer 103 when a voltage is applied to the display device having such a structure. FIG. 5A shows an example in which the scattering degree of emitted light in the light scattering layer 103 is small, and FIG. 5B shows an example in which the scattering degree of emitted light in the light scattering layer 103 is large. According to this, in FIG.
Since almost all of the incident light 110 on the light becomes the straight-out emission light 111, the intensity of the light observed as the emission light of the picture element 105 becomes strong and white display is performed. In FIG. 5B, the incident light 112 on the picture element 105 is strongly scattered and the scattered outgoing light 1
Therefore, the intensity of the light observed as the light emitted from the picture element 105 is weakened and black display is performed.

[0004]

The above-mentioned conventional display device has the following drawbacks. That is, as shown in FIG. 6, the intensity of the light observed as the emitted light of the picture element 105b is not only the straight traveling light 117 from the light scattering layer 103 of the picture element 115 but also the adjacent picture element 114,
Scattered outgoing light 118, 11 from the light scattering layer 103 of 116
It depends on the total amount of light. In this case, picture element 11
When it is desired to display 5 in black, the light scattering layer 103 of the pixel 115
If the light scattering degree is increased, the straight light 117 becomes weaker, but if the scattered outgoing light 118, 119 from the light scattering layer 103 of the adjacent picture elements 1114 and 116 is strong, the light observed as the outgoing light of the picture element 115. Strength does not become sufficiently small.
That is, the light scattering layer 103 of the adjacent picture elements 114 and 116.
There is a case where black display with a sufficiently small light intensity cannot be performed at 115 due to the influence of the scattered emitted lights 118 and 119 from the light, which causes a decrease in the contrast ratio.

The present invention is intended to solve the above problems, and an object thereof is to prevent the display of each picture element from being influenced by the scattered light from the light scattering layer of the picture element adjacent thereto. It is to provide a display device having a contrast ratio.

[0006]

A display device according to the present invention includes an insulating substrate disposed on the light incident side and an electrode formed on the light emitting side, and an electrode disposed on the light emitting side, the electrode being disposed on the light incident side. Light scattering in which the formed insulating layer composed of one or a plurality of stacked layers and the gap between the insulating substrate and the insulating layer are filled, and the scattering degree is controlled by applying a voltage to both electrodes. A layer and, when the insulating layer is composed of one, formed on one surface or both surfaces of the insulating layer, and when composed of a plurality of layers, at least one of both outermost surfaces and boundary surfaces thereof, and has a light transmitting portion. A light-shielding film is provided to achieve the above object.

In a preferred embodiment, the insulating layer is composed of a plurality of layers, the light-shielding film is formed on both outermost surfaces and boundary surfaces of the insulating layer, and in a direction perpendicular to the surface of the insulating substrate. The light transmitting portions are provided so as to coincide with and overlap with each other.

In a preferred embodiment, a plurality of the light transmitting portions are formed for one light shielding film.

[0009]

In the display device of the present invention, since the light-shielding film having the light-transmitting portion matching the distribution of the picture elements is formed in the light-emitting side insulating layer, the light emitted from the light-scattering layer of each picture element is Only the straight outgoing light is transmitted and the scattered outgoing light is blocked by this light shielding film. Therefore, the intensity of the observed light is determined only by the straight outgoing light and is not affected by the scattered outgoing light.

[0010]

EXAMPLES The present invention will be described below based on examples.

FIG. 1 is a cross-sectional view of a matrix type display device using the light scattering element of this embodiment, FIG. 2 is a plan view of the display device of this embodiment seen from the light emitting side, and FIG. [FIG. 3] is a plan view of the display device of the present embodiment viewed from the light incident side.

This display device has the following structure. That is, as shown in FIG. 1, the light scattering layer 6 is filled in the gap between the insulating substrate 5 arranged on the light incident side and the three-layer insulating layer 1 arranged on the light emitting side. The insulating layer 1 is composed of insulating layers 2, 3 and 4, and light-shielding films 7, 8 and 9, 1 are provided on both sides of the insulating layer 2 and on one side of the insulating layers 3 and 4.
0 is formed. In the present embodiment, the insulating layer 2, 3 and 4 will be collectively referred to as the insulating layer 1 when referred to as a whole. The insulating layer 1 is provided with an effective display portion 11 that transmits light and a non-display portion 12 that is the other portion.

Further, it is necessary to provide a means for applying a voltage to the light-scattering layer 6 of each picture element in either or both of the insulating layer 1 and the insulating substrate 5. In this embodiment,
A common electrode (not shown) is formed on almost the entire surface of the insulating layer 2 constituting the insulating layer 1 in contact with the light scattering layer 6.
Further, as shown in FIG. 3, an insulating substrate 5 (not shown)
The pixel electrodes 19 are formed in a matrix on the above so as to match the distribution of the effective display portion 11, and a thin film transistor (T
FT) 20 is formed. The pixel electrode 19 has a larger area than the effective display portion 11, and the TFT 20
A source bus line 21 for supplying a video signal and a gate bus line 22 for supplying a scanning signal are connected to the lines, and the lines 21 and 22 are further connected to external electrode terminals.

The display device having the above structure is manufactured as follows.

First, a chromium film is formed on the insulating layers 2, 3 and 4 by a sputtering method and patterned by a photolithographic method to form light shielding films 7, 8, 9 and 10. In this case, the insulating layers 2 have the same shape as the light-shielding films 7 and 8 so that the matrix-shaped light transmitting portions 17 remain on both surfaces.
Then, on the insulating layers 3 and 4, the light shielding films 9 and 10 having the same shape as the above light shielding film are formed on one surface thereof. Then, the insulating layers 2, 3 and 4 are sequentially arranged so that the surfaces on which the respective light shielding films are formed are not in contact with each other, and as shown in FIG. , And the light transmitting portions 17 which are portions other than the light shielding portion 18 of each substrate are attached so as to coincide with and overlap with each other, and are fixed with a sealing resin. The overlapping light transmitting portion 17 becomes the effective display portion 11, and the light shielding portion 1
8 is the non-display part 12.

The insulating layers 2, 3, obtained as described above,
In the insulating layer 1 made of 4, a common electrode (not shown) made of an ITO film is formed on almost the entire bottom surface of the insulating layer 2. Although the insulating layer is formed of three layers in this embodiment, the number of insulating layers is not limited to this, and one layer may be formed of two layers or four or more layers.

Next, as shown in FIG. 3, a picture is formed on the insulating substrate 5 (not shown) so as to match the distribution of the effective display portion 11 and have a larger area than the effective display portion 11. The element electrodes 19 are formed in a matrix, and the pixel electrodes 19 are formed.
A TFT 20 is formed as a means for supplying a signal to, and a source bus line 21 and a gate bus line 22 are similarly arranged on the insulating substrate 5. Note that a structure in which the pixel electrode 19 and the TFT 20 are provided on the insulating layer 2 forming the insulating layer 1 and the common electrode is formed on the insulating substrate 5 is also possible, contrary to the present embodiment. Further, as a means for supplying a signal to the picture element electrode 19, an active element other than the TFT may be used, or a method of applying a voltage to the light scattering layer 6 of each picture element without using the active element may be used. .

The insulating layer 1 and the insulating substrate 5 formed as described above are attached to each other so that the effective display portion 11 of the insulating layer 1 and the pixel electrode 19 of the insulating substrate 5 overlap each other, and the gap therebetween. Then, a light scattering element is filled in to form the light scattering layer 6.
In this embodiment, a polymer dispersed liquid crystal in which liquid crystal is dispersed in a polymer matrix is used as the light scattering element.
Besides, scattering-type liquid crystals other than polymer-dispersed type, or light-scattering substances not using liquid crystals can be used. After that, the display device of this embodiment is obtained by sealing with a sealing resin.

FIG. 1 shows a state of light emitted from the light scattering layer 6 when a voltage is applied to the obtained display device.
According to it, of the light 13 incident on the light scattering layer 6,
The straight outgoing light 14 having a small degree of scattering passes through the insulating layer 1 without being blocked by the light shielding films 7, 8, 9 and 10, but the scattered outgoing light 15, 16 having a large degree of scattering is provided in the light shielding film 8, respectively.
Since it is blocked by 9, it does not pass through the insulating layer 1. That is, of the light emitted from the light scattering layer 6, the light having a high degree of scattering is shielded by the light shielding films 7, 8, 9 and 10, and thus does not affect the display quality. Therefore, the contrast ratio is higher than that of the conventional display element.

Although a matrix type display device is used in this embodiment, the present invention is not limited to this and can be widely applied to other display devices.

[0021]

As is apparent from the above description, in the display device of the present invention, the light intensity of each picture element to be observed is determined only by the straight light emitted from the light scattering layer of the picture element, and the adjacent picture Since the scattered light emitted from the elementary light scattering layer is not affected, it is possible to realize a display device having a high contrast ratio and good display quality.

[Brief description of drawings]

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

FIG. 2 is a plan view of FIG. 1 viewed from a light emitting side.

FIG. 3 is a plan view of FIG. 1 viewed from a light incident side.

FIG. 4 is a cross-sectional view of a conventional display device.

5 is a cross-sectional view showing states of straight-ahead outgoing light and scattered outgoing light from the light-scattering layer 103 of FIG.

FIG. 6 is a cross-sectional view showing a state in which scattered emission light from the light scattering layer 103 of adjacent picture elements in FIG. 4 influences display.

[Explanation of symbols]

 2, 3, 4 Insulating layer 5 Insulating substrate 7, 8, 9, 10 Light shielding film

Claims (3)

[Claims] 1. An insulating substrate disposed on the light incident side and having an electrode formed on the light emitting side, and one or a plurality of laminated layers disposed on the light emitting side and having an electrode formed on the light incident side. And an insulating layer composed of one, and a light scattering layer which is filled in a gap between the insulating substrate and the insulating layer and whose scattering degree is controlled by applying a voltage to both electrodes. In this case, a display device comprising a light-shielding film having a light-transmitting portion, which is formed on one surface or both surfaces of the insulating layer, and in the case of a plurality of insulating layers, formed on at least one of both outermost surfaces and boundary surfaces. 2. The insulating layer comprises a plurality of layers, the light-shielding film is formed on both outermost surfaces and boundary surfaces of the insulating layer, and overlaps with the surface of the insulating substrate in a direction perpendicular to each other. The display device according to claim 1, wherein the light transmitting portion is provided. 3. The display device according to claim 2, wherein a plurality of the light transmitting portions are formed for one light shielding film.