JPH05135875A - Multicolored luminous thin film el element - Google Patents

Abstract

PURPOSE:To provide a structure of a multicolored luminous thin film EL element needing no use of photolithography or etching for construction of phosphor layers. CONSTITUTION:On a glass substrate, a transparent electrode 1, a 1st insulating layer 2, a 1st phosphor layer 3, a 2nd insulating layer 5, a rear face electrode 6, a 2nd phosphor layer 4, a 3rd insulating layer 7 and a rear face electrode 8 are laminated successively. Luminous electric field intensities and wavelengthes of EL light of the 1st phosphor layer 3 and the 2nd phosphor layer 4 are different, and when an AC voltage is applied between the transparent electrode 1 and the rear face electrode 8, the 2nd phosphor layer 4 between them only can be made luminous. The exfoliation of phosphor layer film due to hydrolysis cannot be generated and manufacturing processes can be simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to E by applying an alternating electric field.
The present invention relates to a thin film EL element that emits L light, and particularly to the structure of a multicolor light emitting thin film EL element.

[0002]

2. Description of the Related Art A thin film EL element used for a display utilizing a phenomenon in which a substance emits fluorescence when an electric field is applied, that is, electroluminescence (EL) is known. An example of the structure of such a thin film EL element that emits two colors will be described with reference to FIG. As shown in the figure, the transparent electrode 1 is laminated on the glass substrate, and the first insulating layer 2 is formed thereon.
, A first phosphor 3 and a second phosphor 4 are formed in a desired pattern thereon, a second insulating layer 5 is laminated thereon, and a back surface is formed on the second insulating layer 5. The electrode 6 is used as the first phosphor 3
The second phosphor 4 has a structure in which it is made to emit light. In order to form the first phosphor 3 and the second phosphor 4 in a desired pattern, for example, the first phosphor is formed on the insulating layer 2 by vapor deposition, sputtering, or the like, and is formed thereon. A photoresist is coated on the substrate and a mask having a desired pattern of the resist is formed by photolithography. In that state, after etching the first phosphor, a second phosphor is formed, and unnecessary portions are removed together with the resist.

[0003]

In the conventional device described above, the photolithography process is performed on the phosphor layer and the phosphor is etched. ZnS-based, CaS-based and other easily hydrolyzed materials are used as the phosphor of the thin film EL element, and film peeling occurs during the manufacturing process, and the phosphor emits light even if a small amount of water is contained. At this time, the high electric field electrolyzes the phosphor layer, and gas generation may cause the film to peel off and stop the light emission.

The present invention has been made in view of the above points, and an object thereof is to provide a structure of a multicolor light emitting thin film EL element which does not use photolithography or etching for forming a phosphor layer. To provide.

[0005]

In the multicolor light emitting thin film EL element of the present invention, a phosphor layer exhibiting different light emission electric field strengths and EL light emission of different wavelengths is provided on a transparent electrode, and an insulating layer is formed in the order of high light emission electric field strength. The back electrodes corresponding to the pattern for causing the phosphor layers to emit light were formed on the insulating layer directly above the phosphor layers, and an alternating voltage was applied between the transparent electrode and each back electrode. At this time, only the phosphor layer directly below the back electrode is configured to emit light.

In the multicolor light emitting thin film EL element, each phosphor layer is caused to emit light at the same voltage by appropriately selecting the thickness and the dielectric constant of each insulating layer.

[0007]

According to the multicolor light emitting thin film EL element of the present invention, the phosphor layers of each color are laminated on the entire surface of the panel, and it is not necessary to use photolithography or etching for pattern formation. Phosphor layers of each color are sequentially laminated between the transparent electrode and the back electrode through an insulating layer in the order of high emission electric field strength, and the phosphor layer closest to the back electrode emits light, and the phosphor layer below it. A voltage that does not emit light can be applied between the transparent electrode and the back electrode to cause the phosphor layer closest to the back electrode to emit light in the pattern between the back electrode and the transparent electrode immediately above it. Further, if each phosphor layer is made to emit light at the same voltage by appropriately selecting the thickness and dielectric constant of each insulating layer, the output voltage of the thin film EL element drive circuit becomes constant and the circuit configuration becomes simple.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multicolor light emitting thin film EL element which is an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. As shown in FIG. 1A, a transparent electrode 1 such as an indium oxide / tin film is laminated on a glass substrate. On top of that, the first insulating layer 2, the first phosphor layer 3, and the second
The insulating layer 5, the back electrode 6, the second phosphor layer 4, the third insulating layer 7, and the back electrode 8 are sequentially stacked.

The first phosphor layer 3 is a red light emitting phosphor (ZnS: SmF) in which samarium fluoride is dispersed in zinc sulfide.
₃ ). The second phosphor layer 4 is formed of a green light emitting phosphor (ZnS: TbF ₃ ) in which terbium fluoride is dispersed in zinc sulfide. FIG. 3 shows the relationship between the applied voltage and the light emission intensity when the thickness of each light emitting body and the insulating layer sandwiching it are the same. As is clear from the figure, the emission field strength of the first phosphor layer is larger than that of the second phosphor layer. Each insulating layer is Si
It is formed of O ₂ , SiN ₄ , Al ₂ O ₃ , Y ₂ O _2, or the like.

First phosphor layer 3 and second phosphor layer 4
Is formed on the entire surface of the panel, but the transparent electrode 1, the back electrode 6 and the back electrode 8 are formed in the pattern shown in FIG. 1 (b). When an alternating voltage is applied between the transparent electrode 1 and the back electrode 6, the portion of the first phosphor layer 3 sandwiched between these electrodes emits light. When an alternating voltage is applied between the transparent electrode 1 and the back electrode 8, the portion of the second phosphor layer 4 sandwiched between these electrodes emits light. An electric field is also applied to the first phosphor layer 3 in this portion, but the intensity thereof does not reach the intensity required for light emission of the required brightness, and the first phosphor layer 3 does not substantially emit light. By adjusting the film thickness and the dielectric constant of each insulating layer, the first phosphor layer 3 and the second phosphor layer 4 can emit light at the same voltage.

FIG. 2 shows a second embodiment of the present invention. As shown in the figure, a transparent electrode 1 such as an indium oxide / tin film is laminated on a glass substrate. On top of that, the first insulating layer 2, the first phosphor layer 3, the second insulating layer 5, the back electrode 6, the second phosphor layer 4, the third insulating layer 7, the back electrode 8 and the third phosphor. The layer 9, the fourth insulating layer 10, and the back electrode 11 are sequentially stacked. The first and second phosphor layers are the same as those used in the first embodiment. The third phosphor layer 7 is a yellow light-emitting phosphor (Z, in which manganese is dispersed in zinc sulfide).
nS: Mn). As is clear from FIG. 3, the emission field strength of the second phosphor layer is larger than that of the third phosphor layer.

The first phosphor layer 3, the second phosphor layer 4, and the third phosphor layer 7 are formed on the entire surface of the panel.
Transparent electrode 1, back electrode 6, back electrode 8 and back electrode 1
1 is formed in a desired pattern. When an alternating voltage is applied between the transparent electrode 1 and the back electrode 6, the portion of the first phosphor layer 3 sandwiched between these electrodes emits light. When an alternating voltage is applied between the transparent electrode 1 and the back electrode 8, the portion of the second phosphor layer 4 sandwiched between these electrodes emits light. An electric field is also applied to the first phosphor layer 3 in this portion, but the intensity thereof does not reach the intensity required for light emission with the required brightness, and the first phosphor layer 3 does not substantially emit light. Transparent electrode 1
When an alternating voltage is applied between the back electrode 11 and the back electrode 11, only the portion of the third phosphor layer 9 sandwiched between these electrodes emits light for the same reason as above. By adjusting the film thickness and the dielectric constant of each insulating layer, the first phosphor layer 3, the second phosphor layer 4, and the third phosphor layer 9 can emit light at the same voltage.

[0013]

According to the multicolor light emitting thin film EL element of the present invention, it is possible to manufacture a multicolor light emitting thin film EL element only by forming the light emitting layer by sputtering or vapor deposition and without performing subsequent processing. Becomes Therefore, the manufacturing cost is reduced.

Further, when a sulfide is used as the phosphor, a photolithography process or a washing process that easily causes hydrolysis is not performed on the phosphor layer, so that a multicolor light emitting thin film EL element can be manufactured with good yield, and Light emission is unlikely to stop due to film peeling during use.

[Brief description of drawings]

FIG. 1 (a) is a sectional view showing the structure of a multicolor light emitting thin film EL element according to a first embodiment of the present invention, and FIG. 1 (b) shows an electrode portion of the same multicolor light emitting thin film EL element. It is a top view shown.

FIG. 2 is a second embodiment of a multicolor light emitting thin film E of the present invention.
It is sectional drawing which shows the structure of L element.

FIG. 3 is a graph showing the light emission characteristics of the light emitting bodies used in the examples of the present invention.

FIG. 4 is a cross-sectional view showing an example of the structure of a conventional multicolor light emitting thin film EL element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 transparent electrode 2 1st insulating layer 3 1st fluorescent substance layer 4 2nd fluorescent substance layer 5 2nd insulating layer 6 back electrode 7 3rd insulating layer 8 back electrode

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[Procedure amendment]

[Submission date] November 19, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be amended] Detailed explanation of the invention

[Correction method] Change

[Correction content]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to E by applying an alternating electric field.
The present invention relates to a thin film EL element that emits L light, and particularly to the structure of a multicolor light emitting thin film EL element.

[0002]

2. Description of the Related Art A thin film EL element used for a display utilizing a phenomenon in which a substance emits fluorescence when an electric field is applied, that is, electroluminescence (EL) is known. An example of the structure of such a thin film EL element that emits two colors will be described with reference to FIG. As shown in the figure, the transparent electrode 1 is laminated on the glass substrate, and the first insulating layer 2 is formed thereon.
, A first phosphor 3 and a second phosphor 4 are formed in a desired pattern thereon, a second insulating layer 5 is laminated thereon, and a back surface is formed on the second insulating layer 5. The electrode 6 is used as the first phosphor 3
The second phosphor 4 has a structure in which it is made to emit light. In order to form the first phosphor 3 and the second phosphor 4 in a desired pattern, for example, the first phosphor is formed on the insulating layer 2 by vapor deposition, sputtering, or the like, and is formed thereon. A photoresist is coated on the substrate and a mask having a desired pattern of the resist is formed by photolithography. In that state, after etching the first phosphor, a second phosphor is formed, and unnecessary portions are removed together with the resist.

[0003]

In the conventional device described above, the photolithography process is performed on the phosphor layer and the phosphor is etched. ZnS-based, CaS-based and other easily hydrolyzed materials are used as the phosphor of the thin film EL element, and film peeling occurs during the manufacturing process, and the phosphor emits light even if a small amount of water is contained. At this time, the high electric field electrolyzes the phosphor layer, and gas generation may cause the film to peel off and stop the light emission.

The present invention has been made in view of the above points, and an object thereof is to provide a structure of a multicolor light emitting thin film EL element which does not use photolithography or etching for forming a phosphor layer. To provide.

[0005]

In the multicolor light emitting thin film EL element of the present invention, a phosphor layer exhibiting different light emission electric field strengths and EL light emission of different wavelengths is provided on a transparent electrode, and an insulating layer is formed in the order of high light emission electric field strength. The back electrodes corresponding to the pattern for causing the phosphor layers to emit light were formed on the insulating layer directly above the phosphor layers, and an alternating voltage was applied between the transparent electrode and each back electrode. At this time, only the phosphor layer directly below the back electrode is configured to emit light.

In the multicolor light emitting thin film EL element, each phosphor layer is caused to emit light at the same voltage by appropriately selecting the thickness and the dielectric constant of each insulating layer.

[0007]

According to the multicolor light emitting thin film EL element of the present invention, the phosphor layers of each color are laminated on the entire surface of the panel, and it is not necessary to use photolithography or etching for pattern formation. Phosphor layers of each color are sequentially laminated between the transparent electrode and the back electrode through an insulating layer in the order of high emission electric field strength, and the phosphor layer closest to the back electrode emits light, and the phosphor layer below it. A voltage that does not emit light can be applied between the transparent electrode and the back electrode to cause the phosphor layer closest to the back electrode to emit light in the pattern between the back electrode and the transparent electrode immediately above it. Further, if each phosphor layer is made to emit light at the same voltage by appropriately selecting the thickness and dielectric constant of each insulating layer, the output voltage of the thin film EL element drive circuit becomes constant and the circuit configuration becomes simple.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multicolor light emitting thin film EL element which is an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. As shown in FIG. 1A, a transparent electrode 1 such as an indium oxide / tin film is laminated on a glass substrate. On top of that, the first insulating layer 2, the first phosphor layer 3, and the second
The insulating layer 5, the back electrode 6, the second phosphor layer 4, the third insulating layer 7, and the back electrode 8 are sequentially stacked.

The first phosphor layer 3 is a red light emitting phosphor (ZnS: SmF) in which samarium fluoride is dispersed in zinc sulfide.
₃ ). The second phosphor layer 4 is formed of a green light emitting phosphor (ZnS: TbF ₃ ) in which terbium fluoride is dispersed in zinc sulfide. FIG. 3 shows the relationship between the applied voltage and the light emission intensity when the thickness of each light emitting body and the insulating layer sandwiching it are the same. As is clear from the figure, the emission field strength of the first phosphor layer is larger than that of the second phosphor layer. Each insulating layer is Si
It is formed of O ₂ , SiN ₄ , Al ₂ O ₃ , Y ₂ O _2, or the like.

First phosphor layer 3 and second phosphor layer 4
Is formed on the entire surface of the panel, but the transparent electrode 1, the back electrode 6 and the back electrode 8 are formed in the pattern shown in FIG. 1 (b). When an alternating voltage is applied between the transparent electrode 1 and the back electrode 6, the portion of the first phosphor layer 3 sandwiched between these electrodes emits light. When an alternating voltage is applied between the transparent electrode 1 and the back electrode 8, the portion of the second phosphor layer 4 sandwiched between these electrodes emits light. An electric field is also applied to the first phosphor layer 3 in this portion, but the intensity thereof does not reach the intensity required for light emission of the required brightness, and the first phosphor layer 3 does not substantially emit light. By adjusting the film thickness and the dielectric constant of each insulating layer, the first phosphor layer 3 and the second phosphor layer 4 can emit light at the same voltage.

FIG. 2 shows a second embodiment of the present invention. As shown in the figure, a transparent electrode 1 such as an indium oxide / tin film is laminated on a glass substrate. On top of that, the first insulating layer 2, the first phosphor layer 3, the second insulating layer 5, the back electrode 6, the second phosphor layer 4, the third insulating layer 7, the back electrode 8 and the third phosphor. The layer 9, the fourth insulating layer 10, and the back electrode 11 are sequentially stacked. The first and second phosphor layers are the same as those used in the first embodiment. The third phosphor layer 7 is a yellow light-emitting phosphor (Z, in which manganese is dispersed in zinc sulfide).
nS: Mn). As is clear from FIG. 3, the emission field strength of the second phosphor layer is larger than that of the third phosphor layer.

The first phosphor layer 3, the second phosphor layer 4, and the third phosphor layer 7 are formed on the entire surface of the panel.
Transparent electrode 1, back electrode 6, back electrode 8 and back electrode 1
1 is formed in a desired pattern. When an alternating voltage is applied between the transparent electrode 1 and the back electrode 6, the portion of the first phosphor layer 3 sandwiched between these electrodes emits light. When an alternating voltage is applied between the transparent electrode 1 and the back electrode 8, the portion of the second phosphor layer 4 sandwiched between these electrodes emits light. An electric field is also applied to the first phosphor layer 3 in this portion, but the intensity thereof does not reach the intensity required for light emission with the required brightness, and the first phosphor layer 3 does not substantially emit light. Transparent electrode 1
When an alternating voltage is applied between the back electrode 11 and the back electrode 11, only the portion of the third phosphor layer 9 sandwiched between these electrodes emits light for the same reason as above. By adjusting the film thickness and the dielectric constant of each insulating layer, the first phosphor layer 3, the second phosphor layer 4, and the third phosphor layer 9 can emit light at the same voltage.

[0013]

According to the multicolor light emitting thin film EL element of the present invention, it is possible to manufacture a multicolor light emitting thin film EL element only by forming the light emitting layer by sputtering or vapor deposition and without performing subsequent processing. Becomes Therefore, the manufacturing cost is reduced.

Further, when a sulfide is used as the phosphor, a photolithography process or a washing process that easily causes hydrolysis is not performed on the phosphor layer, so that a multicolor light emitting thin film EL element can be manufactured with good yield, and Light emission is unlikely to stop due to film peeling during use.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hironori Nagumo 2-17-5 Shibuya, Shibuya-ku, Tokyo Ken-Uddo Co., Ltd.

Claims (2)

[Claims] 1. Phosphor layers exhibiting different emission field strengths and EL emissions of different wavelengths are sequentially laminated on a transparent electrode through an insulating layer in the order of higher emission field strengths, and the insulating layers directly above each phosphor layer. A back electrode corresponding to the pattern for causing the phosphor layer to emit light is formed on top of the phosphor layer, and when an alternating voltage is applied between the transparent electrode and each back electrode, only the phosphor layer directly below the back electrode emits light. A multicolor light emitting thin film EL device constructed. 2. The multicolor light emitting thin film EL element according to claim 1, wherein each phosphor layer is caused to emit light at the same voltage by appropriately selecting the thickness and dielectric constant of each insulating layer.