KR100326464B1 - Electroluminescent display device - Google Patents

Abstract

The present invention relates to an electroluminescent display device that can minimize reflection of external light and loss of light emitted from a fluorescent layer by suppressing light reflection on a glass substrate surface.

A glass substrate, a first electrode layer formed on one surface of the glass substrate, a second electrode layer which is combined with the first electrode layer to form a plurality of pixels, and is disposed between the first electrode layer and the second electrode layer. A fluorescent layer emitting light by an alternating current voltage applied to the second electrode layer, a pair of insulating layers disposed between the first electrode layer, the fluorescent layer and the second electrode layer, and a high refractive index material layer provided on both surfaces of the glass substrate A plurality of pairs of low refractive index material layers are stacked to provide an electroluminescent display including an antireflection film selectively transmitting visible light in a wavelength range of 380 to 780 nm.

Description

Electroluminescent Display Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescent display, and more particularly, to an electroluminescent display capable of minimizing light reflection on a surface of a glass substrate to minimize external light reflection and loss of light emitted from a fluorescent layer.

In general, an electroluminescent device (ELD) is a display device using an electroluminescent (EL) phenomenon in which light is emitted from a phosphor by an electric field, and includes a pair of electrodes on a glass substrate with a fluorescent layer interposed therebetween. A known structure is provided in which a fluorescent layer is emitted by applying an alternating current (AC) voltage to an electrode, and a multilayer provided on a glass substrate is usually made of a thin film.

The electroluminescent display having the above structure is called a thin film ELD (TFELD), and in this device, the positive electrode layer and the fluorescent layer formed on the glass substrate and the insulation for separating the electrode layer from the fluorescent layer The layer is formed into a thin film by electron beam vacuum deposition, sputtering, or the like.

The positive electrode layer is mainly formed of a metal such as Al or a transparent electrode such as indium tin oxide (ITO), and these electrode layers form respective pixels and function similar to the data electrode and the scan electrode.

Meanwhile, in order to prevent breakdown of a dielectric, which is a problem occurring in a thin film electroluminescent display, an electroluminescent display (TDELD) having a thick film insulating layer has appeared, and related technologies Examples include electroluminescent laminates described in US Pat. No. 5,432,015.

However, the electroluminescent display according to the prior art is mostly provided with a multi-layered film on the glass substrate, the glass substrate has an external light reflectance of about 4%, 4% of the light incident on the glass substrate from the outside where the observer is located While reflecting 4% of the light emitted from the fluorescent layer.

As a result, a part of the screen implemented in the display device is obscured by external light due to the high reflectance on the surface of the glass substrate, which causes a problem of deteriorating display quality, such as causing a loss of light emitted from the fluorescent layer and lowering luminance. .

Therefore, the present invention is designed to solve the above problems, an object of the present invention is to suppress the light reflection on the surface of the glass substrate to minimize the external light reflection while improving the field emission efficiency of the light emitted from the fluorescent layer It is to provide a display device.

1 is a cross-sectional view of an electroluminescent display according to the present invention.

2 is an enlarged view of a portion A of FIG. 1;

In order to achieve the above object, the present invention,

Glass substrate,

A first electrode layer formed on one surface of the glass substrate,

A second electrode layer combined with the first electrode layer to form a plurality of pixels;

A fluorescent layer disposed between the first electrode layer and the second electrode layer to emit light by an alternating voltage applied to the first and second electrode layers;

A pair of insulating layers disposed between the first electrode layer, the fluorescent layer, and the second electrode layer;

An electroluminescent display device is provided on both surfaces of the glass substrate and includes means for selectively transmitting light in a visible light region.

The above means consists of an antireflection film in which a plurality of high refractive index material layers and a low refractive index material layer are stacked, and selectively transmits visible light in the wavelength range of 380 to 780 nm.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of an electroluminescent display according to the present embodiment. As shown in FIG. 1, an electroluminescent display includes a transparent glass substrate 2 and a first electrode layer 4 formed on one surface of the glass substrate 2. The first insulating layer 6 is formed on the entire surface of the glass substrate 2 so as to surround the first electrode layer 4, the fluorescent layer 8 and the second insulating layer formed on the surface of the first insulating layer 6. The second electrode layer 12, which is formed on the layer 10, the second insulating layer 10, and constitutes a plurality of pixels in combination with the first electrode layer 4, and surrounds the multilayer film formed on the glass substrate 2. A protective film 14 is included.

The glass substrate 2 and the first electrode layer 4 are made of a transparent material to transmit the light emitted from the fluorescent layer 8 to the user, so that the first electrode layer 4 is a transparent electrode such as ITO. It is preferable to form.

The first electrode layer 4 and the second electrode layer 12 disposed with the fluorescent layer 8 interposed therebetween are formed in a stripe pattern so as to vertically cross each other so that the intersection portion forms one pixel. It functions as a data electrode and a scan electrode, respectively.

Here, the first electrode layer 4 is made of a transparent electrode, while the second electrode layer 12 is formed of a metal electrode such as Al.

The first and second insulating layers 6 and 10 disposed between the first and second electrode layers 4 and 12 and the fluorescent layer 8 may include Y ₂ O ₃ , Ta ₂ O ₅ , Al ₂ O _3, formed of a dielectric material such as Si ₃ N _4, for a thick film dielectric layer comprises a dielectric material, such as SrTiO ₃ and PbTiO ₃ or PbNbO _3. As such, when the insulating layers are made of a material having a high dielectric value, a high electric field may be induced in the fluorescent film 8 even at a low driving voltage, thereby lowering the driving voltage of the display device.

Subsequently, the fluorescent layer 8 disposed between the first and second insulating layers 6 and 10 is made of a material such as ZnS: Mn and applied to the first electrode layer 4 and the second electrode layer 12. It emits light by the alternating current voltage.

According to this configuration, when an alternating current voltage is applied to the first electrode layer 4 and the second electrode layer 12 from an external circuit, each pixel in the fluorescent layer 8 has different luminance values according to the intensity of the alternating voltage. A predetermined image may be realized by emitting light, and when the color filter is further provided, the image to be implemented may be colorized.

In this case, the electroluminescent display according to the present embodiment further includes means for selectively transmitting visible light on both surfaces of the glass substrate 2 in order to suppress light reflection on the surface of the glass substrate 2. The means comprises an antireflection film 16 having a high transmittance to visible light, and the antireflection film 16 selectively transmits visible light, which is a region of light that can be recognized by a person, and light in a wavelength region other than visible light. By reflecting silver, it serves to suppress reflection of light, especially visible light, on the surface of the glass substrate 2.

FIG. 2 is an enlarged view of a portion A of FIG. 1 showing an enlarged view of the antireflection film, and as shown, the antireflection film 16 has a multilayer structure of a high refractive index material layer 18 and a low refractive index material layer 20. In addition, the layers of the high refractive index material layer 18 and the low refractive index material layer 20 are integrally stacked on the basis of a pair of layers bonded to each other.

More specifically, the high refractive index material layer 18 of the antireflection film 16 is made of, for example, TiO ₂ having a refractive index of 2.1 to 2.6, and the low refractive index material layer 20 has SiO ₂ and Al having a refractive index of 1.46 to 1.60. ₂ O ₃ and the like.

Since the refractive index of the glass substrate 2 is as low as about 1.4, the high refractive index material layer 18 and the low refractive index material layer 16 are repeatedly stacked from the surface of the glass substrate 2.

Since the glass substrate 2 has a low refractive index of about 1.4, the high refractive index material layer 18 and the low refractive index material layer 20 are repeatedly stacked from the surface of the glass substrate 2.

As shown in FIG. 1, the antireflection film 16 having such a structure is attached to both the outer surface of the glass substrate 2 to which external light is incident and the inner surface where the fluorescent layer 8 is located.

Here, each of the high refractive index material layers 18 and the low refractive index material layers 20 may have a physical layer thickness d and an optical layer thickness d 'expressed by Equations 1 and 2 below. Is done.

d = λ / (2n)

d '= λ / 2

Is the wavelength of light, in particular 380 to 780 nm, which is the wavelength of visible light, and n represents the refractive index.

In this case, the optical layer thickness λ / 2 of each of the high refractive index material layer 18 and the low refractive index material layer 20 means a phase difference of 180 ° when λ is viewed as one period of wavelength.

As a result, when a specific wavelength, that is, visible light, enters the anti-reflection film 16, the phase difference of incident light becomes 180 ° when passing through each of the high refractive index material layer 18 and the low refractive index material layer 20. Becomes ± 0 ° and does not modulate the periodicity of the original visible light incident on the antireflection film 16, resulting in high transmittance.

That is, the anti-reflection film 16 transmits most of the visible light while reflecting light of different wavelengths in the same principle as above.

In addition, as the pair of high refractive index material layers 18 and the low refractive index material layer 20 are stacked in a larger number, the transmittance of visible light becomes higher. The antireflection film 16 includes a pair of high refractive index material layers 18 and a low refractive index material. The layer 20 has a structure in which at least one or more layers are repeatedly stacked.

Therefore, in both the case where external light is incident on the outer surface of the glass substrate 2 and when the light emitted from the fluorescent layer 8 is incident on the inner surface of the glass substrate 2, both surfaces of the glass substrate 2 are provided. The antireflection film 16 attached to the light transmits most of the visible light, thereby minimizing light loss and external light reflection.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

As described above, the electroluminescent display device according to the present invention transmits most of the visible light incident on the glass substrate from the outside by attaching an antireflection film to both surfaces of the glass substrate, thereby effectively preventing the degradation of the image quality such as the screen obscured by the reflection of external light. At the same time, most of the visible light incident on the glass substrate is transmitted from the fluorescent layer, thereby reducing the luminance due to light loss.

Claims (6)

A glass substrate; A first electrode layer formed on one surface of the glass substrate; A second electrode layer combined with the first electrode layer to form a plurality of pixels; A fluorescent layer disposed between the first electrode layer and the second electrode layer to emit light by an alternating voltage applied to the first and second electrode layers; A pair of insulating layers disposed between the first electrode layer, the fluorescent layer, and the second electrode layer; Electroluminescent display devices provided on both surfaces of the glass substrate, and including means for selectively transmitting light in a visible light region. The method of claim 1, And the means comprises an antireflection film in which a plurality of high refractive index material layers and low refractive index material layers are stacked. The method of claim 2, An electroluminescent display device in which the high refractive index material layer is made of TiO ₂ . The method of claim 2, And the low refractive index material layer is selected from the group consisting of SiO ₂ and Al ₂ O ₃ . The method of claim 2, And an antireflection film having a structure in which a pair of high refractive index material layers and a low refractive index material layer are repeatedly stacked at least once. The method of claim 2, And an anti-reflection film having a structure in which a high refractive index material layer and a low refractive index material layer are sequentially stacked from a surface of a glass substrate.