JPH1167458A - Electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an element that emit light with high efficiency and luminescence by placing a first excitation layer formed from a transparent light excitation film mixed transparetly with a light excitation material such as a fluorescent coating or a fluorescent dye, or from a coating by means of printing or the like ahead of a luminescent layer and hence, exciting more the emission amount emitted from the luminescent layer by the first excitation layer. SOLUTION: A transparent light excitation film or a coating formed by means of printing or the like to be used as a first excitation layer 6 is placed on a transparent conductive film 1. A sealing film 10 seals both the first excitation layer 6 and a back electrode layer 4. When a voltage is applied to a part between the conductive film 1 and the back electrode layer 4, a luminescent layer 2 emits light which is directed to an insulating layer 3 on the back side and the first excitation layer 6 on the front side. While the emitted light to the insulating layer 3 side and the reflection quantity from the back side are the same as those of a conventional one, the light directed to the excitation layer 6 side where the light excitation component produced by the light excitation material included in the first excitation layer 6 is added to the emitted light component of the luminescent layer 2 is emitted forward from the sealing film 10 so that high luminescence light emission can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescence device which emits light by applying an AC or DC voltage between a pair of electrodes and is used for a liquid crystal backlight or the like.

[0002]

2. Description of the Related Art An electroluminescent element is a thin planar light emitting element. In order to obtain high efficiency, a reflective back electrode layer sheet made of a metal sheet such as aluminum is used to reflect light leaking from a dielectric breakdown voltage layer to a front surface. Means and the like have been used.

[0003]

The electroluminescent element is used for a backlight of a product with a handy type LCD and the like, and the driving power of the product is a small power source such as a dry battery or a button battery. There has been a strong demand to reduce the burden of battery replacement by extending battery life by consuming the battery.

On the other hand, an electroluminescent element is
In the conventional products, when the current consumption is low, uneven light emission is likely to occur, and the display on the LCD is difficult to see. Conversely, in order to emit light with high luminance, it is necessary to apply a high voltage and a high current at a high frequency, and there is a problem that the life is shortened.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional electroluminescent device, and has as its object to reduce the current consumption under the conventional luminance generating condition or to increase the current consumption at the same level as the conventional current consumption. It is an object of the present invention to provide an electroluminescent element that emits light with high efficiency and high luminance that realizes luminance.

[0006]

In order to achieve the above-mentioned object, an electroluminescent device according to the present invention comprises an excitation layer containing a photoexciting material such as a fluorescent pigment or a fluorescent dye so as to be excited by a light emitted from a light emitting layer. Alternatively, a light emission excitation layer in which a phosphor is mixed is provided in the light emission layer, and high-intensity light emission is performed by adding an induced light excitation component to the light emission component of the light emission layer.

That is, a first excitation layer made of a transparent light excitation film or a coating such as printing in which a light excitation material is mixed in a range allowing light transmission is disposed on the front side of the light emitting layer.

Further, a second excitation layer made of a photoexciting material film mixed with a photoexciting material or a coating such as printing is disposed on the rear side of the light emitting layer.

Furthermore, a photoexciting material is mixed into the light emitting layer and the insulating layer.

[0010]

The photoexciting material uses a daylight fluorescent pigment or the like, and emits light when stimulated by irradiation of artificial light such as daylight, a fluorescent lamp, a mercury lamp, etc., and emits no light when the irradiation is stopped.

FIG. 6 is an explanatory diagram of a spectral distribution in which a photoexciting material is applied on a white base and the spectral distribution of the fluorescent color under the standard light source C is obtained. The fluorescent color A, which is the excitation component of the light excitation material, is divided into a fluorescent component B and a pure reflection component C in which the fluorescent component is not mixed. The ordinary color D, which consists only of reflected light having substantially the same hue as the photoexciting material, absorbs a specific part of the incident white light, emits heat energy and the like other than light, and reflects the remainder to reflect the residue. Although it appears to be attached, the fluorescent color A has a slightly higher intensity than the residual ordinary color D that selectively absorbs incident white light, and the energy of the absorbed incident light is used as fluorescence in addition to heat energy. Radiate again. Since the energy of the fluorescent light is naturally smaller than the energy of the incident light, the frequency is reduced and the wavelength is increased. As a result, the wavelength range of the reflection component and the wavelength range of the fluorescent component are close to each other, and the two components are combined to obtain a spectrum having a high peak component as seen in the fluorescent color A. When combined with electroluminescence,
Since the excitation component of the photoexciting material, which is stronger than the reflected light, is added to the emission component of the electroluminescence itself, the electroluminescence element can emit light with high luminance.

[0012]

FIG. 4 and FIG. 5 are cross-sectional views of a conventional electroluminescent device. In the electroluminescent element, an insulating layer 3 and a light emitting layer 2 are sandwiched between a transparent conductive film 1 having a transparent conductive layer formed on the lower surface and a back electrode layer 4, and the transparent conductive film 1 and the back electrode layer 4 are interposed therebetween. An AC or DC voltage is applied to the light emitting layer 2. The light-emitting layer 2 is an electroluminescent body that is adhered to the transparent conductive layer formed on the lower surface of the transparent conductive film 1 and is formed of zinc sulfide or the like. As the transparent conductive film 1, an ITO electrode film having indium tin oxide as a transparent conductive layer is widely used.
In FIG. 4, the transparent conductive film 1 and the back electrode layer 4 are covered with the sealing film 10. However, the light-emitting layer 2 is treated so as not to absorb moisture, and some of them do not have the sealing film 10.

1 (a), 1 (b), 1 (c). (D),
(E) is an explanatory diagram of a first embodiment of the electroluminescence of the present invention. In the drawing, those having the same symbols as those in FIG. 4 have the same names and the same functions. FIG.
(A), (b), (c), (d), and (e) show the conventional electroluminescent elements shown in FIG. 5, that is, the laminated transparent conductive film 1, light emitting layer 2, insulating layer 3, FIG. 3 is a diagram showing a first embodiment of the electroluminescent device of the present invention in which a first excitation layer 6 made of a transparent light excitation film or the like is disposed in front of the light emitting layer 2 in the back electrode layer 4.

In FIG. 1A, a transparent light-exciting film or a coating, such as a print, serving as a first excitation layer in which a light-exciting material such as a fluorescent pigment or a fluorescent dye is mixed in a light-transmittable range is formed on the surface of the transparent conductive film 1. Are arranged. Sealing film 1
Reference numeral 0 denotes a sealing including the first excitation layer 6 and the back electrode layer 4. Here, when a voltage is applied between the conductive film 1 and the back electrode layer 4, the light emitting layer 2 emits light. Light emission of the light emitting layer 2 is directed to the insulating layer 3 on the back side and the first excitation layer 6 on the front side. In FIG. 1A, the amount of light emission toward the insulating layer 3 and the amount of reflection from the back side are considered to be the same as those in the related art, so if only the light of the light emitting layer 2 directed to the first excitation layer 6 is considered. good. In addition to the light-emitting component of the light-emitting layer 2, the excitation component of light excited by the photoexciting material contained in the first excitation layer 6 is emitted forward from the sealing film 10, so that
High brightness light emission is obtained. In addition, the fluorescent color A due to the photoexciting material remains for a short time after the light of the light emitting layer 2 disappears, and the resolution is low due to the influence of internal reflection. Play a role to do.

FIG. 1B shows a state in which the sealing film 10 is removed from the electroluminescent element shown in FIG. 1A, and the function of the first excitation layer 6 is the same. Also, in FIG. 1C, the first surface of the sealing film 10 of the conventional electroluminescent element shown in FIG.
The excitation layer 6 is adhered, and although the light of the light emitting layer 2 is attenuated by the sealing film 10, the sealing film 10 is extremely thin. Therefore, the first excitation layer similar to that of FIG. The action of

FIGS. 1D and 1E show that a first excitation layer 6 made of a transparent light excitation film or a transparent coating material mixed with an excitation material is provided between the light emitting layer 2 and the transparent conductive film 1. Since the first excitation layer is close to the light emitting layer 2 as compared with FIG. 1A, loss on the way is also reduced, and higher luminance can be expected.

2 (a), 2 (b) and 2 (c) show the conventional electroluminescent element shown in FIG. 5, that is, the laminated transparent conductive film 1, light emitting layer 2, insulating layer 3, back electrode layer 4. FIG. 4 is a diagram showing a second embodiment of the electroluminescent device of the present invention in which a second excitation layer 7 made of a photoexcitation film or a coating such as printing is disposed on the back surface of the light emission layer 2.

Referring to FIG. 2A, the back surface of the back electrode layer 4 is a photo-exciting film or a printing coating, such as an aluminum laminate sheet, as a second exciting material 7 mixed with a photo-exciting material such as a fluorescent pigment or a fluorescent dye. It is arranged in. The sealing film 10 includes a transparent conductive film 1 and a second
And the excitation layer 7 is sealed. Here, when a voltage is applied between the conductive film 1 and the back electrode layer 4, the light emitting layer 2
Emits light. Light emitted from the light emitting layer 2 is directed to the transparent conductive film 1 on the front side and the back electrode layer 4 on the back side. FIG. 2 (a)
In FIG. 5, the component reflected on the surface of the back electrode layer 4 in the direction opposite to the light emission toward the transparent conductive film 1 and the opposite side is shown in FIG.
Is considered to be the same as the conventional example shown in FIG.

However, since the back electrode layer 4 is a thin aluminum laminate sheet or the like, or is formed by printing a conductive material or the like, the back electrode layer 4 is microscopically porous and leaks light emitted from the light emitting layer 2. This leakage component enters the second excitation layer 7 and the light is excited by the light excitation material. A part of the excited light returns toward the back electrode layer 4 and the light emitting layer 2 and goes to the transparent conductive film 1 side. By such a component that has returned and transmitted, it is possible to emit light with higher luminance than the conventional example shown in FIG.

FIG. 2B shows a state in which the sealing film 10 is removed from the electroluminescent element shown in FIG. 2A, and the function of the second excitation layer 7 is the same. FIG. 2
In FIG. 2C, titanium oxide or the like is dispersed and applied on the back surface of the electroluminescent element shown in FIG. 2B, or a reflective layer 11 made of a laminate sheet is provided. The light excited by the layer 7 returns to the side of the transparent conductive film 1 without leaking and is transmitted therethrough.
(A) It is possible to emit light with higher luminance than the example of FIG.

FIGS. 3A and 3B show a third embodiment of the electroluminescent device of the present invention in which a light-exciting material is mixed into the light-emitting layer 2 to form a light-emitting layer 8, and FIG. The film 10 is sealed including the transparent conductive film 1 and the back electrode layer 4. Mixing the photoexciting material into the light emitting layer 2 can emit light with high luminance since the light emitting component of the light emitting layer 2 itself and the exciting component of the photoexciting material emit light.

FIGS. 3 (c) and 3 (d) show an electroluminescence device in which a photoexciting material is mixed into an insulating layer 3 provided between the light emitting layer 2 and the back electrode layer 4 to form an insulating excitation layer 9. In the embodiment, FIG. 3A is sealed with a sealing film 10.

4 (a), (b), (c),
(D) is a fourth example of the electroluminescent device of the present invention using two excitation layers, the second excitation layer 7 and the insulating excitation layer 9.
FIG. 9 is a diagram showing an example of how the second excitation layer 7 and the insulating excitation layer 9 are combined. In addition, a combination of two or more excitation layers may be used, and high-luminance light emission can be achieved similarly. On the other hand, if it is assumed that the brightness is the same as the conventional brightness, it is possible to reduce the amount of light emitted from the light emitting layer 2 by reducing the current and the like. In this case, uneven light emission is averaged by the afterglow action of the photoexciting material and the reflected light component between the photoexciting materials, thereby enabling uniform surface light emission.

[0024]

According to the electroluminescent device of the present invention, the first excitation layer 6 containing the photoexciting material as described
The second excitation layer 7 is disposed so as to be sandwiched between the components of the electroluminescent element, or a photoexciting material is mixed into the main constituent layers of the electroluminescent element such as the light emitting layer 2, the insulating layer 3, and the back electrode layer 4. There is an effect that higher-luminance light emission than before can be achieved.

Further, since this high-luminance light emission is independent of the voltage and current applied between the transparent conductive film 1 and the back electrode layer 4 and is independent, the amount of power required per unit light emission is reduced. As a result, the luminous efficiency increases.

Further, the photoexciting material has an afterglow effect, and the light emission is averaged by reflection between the photoexciting materials, thereby enabling uniform surface light emission. For this reason, it was not possible to reduce the current below a certain level due to the occurrence of uneven light emission in the past.However, the photoexciting material enabled a visually uniform light emission and realized a slightly dark surface emission leading to a low sub-current. Battery that will be used as power source due to longer life and lower power consumption,
This has the effect of extending the life of the battery.

[Brief description of the drawings]

FIG. 1 shows a first example of the electroluminescent device of the present invention.
FIG.

FIG. 2 shows a second example of the electroluminescent device of the present invention.
FIG.

FIG. 3 shows a third example of the electroluminescent device of the present invention.
FIG.

FIG. 4 shows a fourth example of the electroluminescent device of the present invention.
FIG.

FIG. 5 is an explanatory view of a conventional electroluminescent element.

FIG. 6 is an explanatory diagram of a spectral distribution according to the electroluminescent device of the present invention.

[Explanation of symbols]

 1-transparent conductive film 2-light-emitting layer 3-insulating layer 4-back electrode layer 6-first excitation layer 7-second excitation layer 8-emission excitation layer 9-insulation excitation layer 11-reflection layer

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[Procedure amendment]

[Submission date] December 24, 1997

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

FIG. 3

FIG. 5

FIG. 6

FIG. 4

Claims (3)

[Claims] 1. A transparent conductive film, a light emitting layer, an insulating layer,
In the electroluminescence obtained by laminating the back electrode layer, a first excitation layer made of a transparent light excitation film or a coating such as printing mixed with a photoexciting material such as a fluorescent pigment or a fluorescent dye in a light-transmittable range is used. An electroluminescent device, which is disposed on the front side and emits high-luminance by further exciting light emitted from the light emitting layer by the first excitation layer. 2. A transparent conductive film, a light emitting layer, an insulating layer,
In the electroluminescence obtained by laminating the back electrode layer, a second excitation layer made of a coating such as a photoexcitation film or printing mixed with a photoexcitation material such as a fluorescent pigment or a fluorescent paint is arranged on the back side of the light emission layer, and light emission is performed. An electroluminescent device characterized in that, of the light emitted from a layer, a component which goes to the backside is excited to emit light and is reflected to the front surface to emit light with brightness. 3. A transparent conductive film, a light emitting layer, an insulating layer,
In the electroluminescence obtained by laminating the back electrode layer, a light-exciting material such as a fluorescent pigment or a fluorescent paint is mixed into the light-emitting layer and the insulating layer to form a light-emitting layer and an insulating layer. An electroluminescent element, which emits light with a luminance corresponding to an amount of excited light emission.