JP3388796B2 - Inorganic dispersed light emitting device and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic dispersion type light emitting device having a high luminance, little unevenness in light emission, and an excellent withstand voltage and an efficient manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as an inorganic dispersion type light emitting device, one having a structure shown in FIG. 2 and FIG. 4 is known, and these are widely used for applications such as measuring instruments for automobiles and decoration of show windows. ing.

That is, in the conventional inorganic dispersion type light emitting device (flat type) shown in FIG. 2, an insulating reflection layer 2 made of white enamel and a phosphor are provided on a metal base 1 represented by stainless steel. It is configured by sequentially forming a phosphor light emitting layer 3 dispersed in an enamel and a transparent conductive film 5 such as an ITO film.

An electrode (not shown) provided on the transparent conductive film 5 and an electrode (not shown) provided on the metal base 1 are
By electrically connecting with a lead wire or the like and applying a voltage from a power source, an electric field is generated in the phosphor light emitting layer 3, and the phosphor emits light.

In the conventional inorganic dispersion type light emitting device shown in FIG. 2, the white insulating reflection layer 2 provided between the metal base 1 and the phosphor light emitting layer 3 improves the withstand voltage and efficiently emits light. It is preferable to use a material having a high dielectric constant in order to prevent the loss of the electric field, since it contributes to the visual recognition to the observer, but the width of the material to be selected is narrow, and the dielectric constant of the phosphor light emitting layer 3 is The reality is that it is difficult to find a material that exceeds this.

Further, in order to reduce the loss of the electric field, it is also possible to make the thickness of the insulating reflection layer 2 as thin as possible, but in the case of using enamel glaze or glass frit as the material of the insulating reflection layer 2. It is difficult to reduce the film thickness to 30 μm or less, and even if the film thickness can be reduced, the original insulating property of the insulating reflection layer 2 and the function as a white reflection layer are deteriorated. It included the problem of being lost.

In the conventional inorganic dispersion type light emitting device shown in FIG. 2, the phosphor light emitting layer 3 has a phosphor particle 3a as a binder (hollow) as shown in an enlarged view of FIG.
The phosphor light-emitting layer 3 has a structure dispersed in 3b.
Does not necessarily have a smooth surface in which the phosphor particles 3a are completely embedded in the binder 3b, and usually the phosphor particles 3a are partially exposed on the surface of the phosphor light emitting layer 3. .

Therefore, when the thin transparent conductive film 5 is formed on the phosphor light emitting layer 3, not only the exposed phosphor particles 3a cause unevenness on the surface of the transparent conductive film 5, but also the exposed phosphor. Since the particles 3a broke the transparent conductive film 5 and jumped out to the outside to generate the disconnection portion 5x, many phosphor particles 3a which did not shine even when an electric field was applied were generated, and the non-emission points were observed as a collection of fine points. There is a problem that uneven light emission is caused, and the overall light emission luminance tends to decrease.

On the other hand, in the conventional inorganic dispersion type light emitting device shown in FIG. 4, the transparent protective layer 4 made of enamel or polymer is provided between the phosphor light emitting layer 3 and the transparent conductive film 5 to provide the above-mentioned structure. This is a mode in which unevenness in light emission and a decrease in brightness due to the exposure of the phosphor particles 3a are improved. It has become.

However, in the conventional inorganic dispersion type light emitting device shown in FIG. 2, one of the upper and lower insulating layers (2, 4) is used.
Since only one of them can secure a sufficient withstand voltage, an increase in the number of insulating layers causes a disadvantage of a loss of electric field, that is, a reduction of an electric field substantially related to the emission brightness applied to the phosphor light emitting layer 3. become.

In order to recover the loss of the electric field in this case, if the formation of the lower insulating reflective layer 2 is omitted, the phosphor is deteriorated by the elution of metal ions from the metal base 1, and the phosphor emitting layer 3 is baked. In this case, there arise problems that the adhesiveness to the metal base 1 is deteriorated and the brightness is reduced due to the disappearance of the white reflective layer.

[0012]

The present invention has been achieved as a result of investigations for solving the problems of the above-mentioned conventional inorganic dispersion type light emitting device.

Therefore, an object of the present invention is to provide an inorganic dispersion type light emitting device which has high brightness and little unevenness in light emission and is excellent in withstand voltage, and a method for efficiently manufacturing the inorganic dispersion type light emitting device. It is in.

[0014]

In order to achieve the above object, the inorganic dispersion type light emitting device of the present invention is a phosphor light emitting device in which a silica coating layer and a phosphor are dispersed in a enamel on the surface of a metal substrate. An inorganic dispersion-type light emitting device in which a layer, a transparent protective layer, and a transparent conductive film are sequentially formed, and the metal substrate and the transparent conductive film are electrically connected to each other.
The silica is formed by forming a thin cover layer having a thickness of 0.1 to 1 μm.
The metallic glossy surface between the coating layer and the metal base is used as a reflective film.
It is characterized by being used .

Further, the method for producing an inorganic dispersion type light emitting device of the present invention comprises applying silica sol to the surface of a metal base and applying nitrogen.
The thickness of the silica coating layer is set to 0.1 by firing in a gas atmosphere.
After being formed as thin as 1 μm , a phosphor emitting layer, a transparent protective layer and a transparent conductive film are sequentially formed on the silica coating layer .

[0016]

In the inorganic dispersion type light emitting device of the present invention, since the silica coating layer is used instead of the conventional insulating reflection layer, not only the loss of the electric field due to the insulating reflection layer can be eliminated, but also the silica coating layer allows the phosphor to be used. It is possible to adequately compensate for the above-mentioned protection, the adhesiveness between the phosphor light-emitting layer and the metal base, the brightness, etc., and to exhibit the desirable characteristics of high brightness, little emission unevenness, and excellent dielectric strength.

According to the method for manufacturing an inorganic dispersion type light emitting device of the present invention, the silica coating layer has a thickness of 0.1 to 1 μm.
In addition to being able to form a thin film, the silica coating layer does not oxidize the metal base during firing, so even if the conventional insulating reflection layer with a thickness of 30 μm or more is omitted, the silica coating layer and metal The function as a reflection film can be exerted on the metallic glossy surface between the base and the substrate, and a high-brightness inorganic dispersion-type light-emitting device in which light emission attenuation is sufficiently suppressed can be efficiently manufactured.

Therefore, according to the present invention, the inorganic dispersion type light emitting device can be manufactured more efficiently than ever before.
Moreover, the inorganic dispersion type light emitting device of the present invention has high emission brightness,
Since it has high reliability in light emission unevenness and withstand voltage, it can be widely used, for example, as a pointer of an automobile instrument or as a decoration of a show window.

[0019]

Embodiments of the inorganic dispersion type light emitting device and the method of manufacturing the same according to the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the inorganic dispersion type light emitting device of the present invention.

In FIG. 1, parts having the same structure as the above-mentioned conventional example will be described using the same reference numerals as those shown in FIGS.

Referring to FIG. 1, an inorganic dispersion type light emitting device of the present invention comprises a silica coating layer 6, a phosphor light emitting layer 3 in which a phosphor is dispersed in enamel, a transparent protective layer 4, and a metal base 1. A transparent conductive film 5 is sequentially formed, and an electrode (not shown) provided on the metal base 1 and an electrode (not shown) provided on the transparent conductive film 5 are connected to each other by a lead wire such as an enamel wire. It is configured by being electrically connected to the power source via the.

The metal base 1 is made of a metal selected from decarbonized steel or stainless steel in the form of a substrate, and the thickness of the metal base 1 when forming a flat inorganic dispersion type light emitting device is 0.5. It is desirable to set it to about 2.0 mm.

The metal base 1 has a silica coating layer 6
It is desirable that the adhesion with the silica coating layer 6 is improved by thoroughly washing and removing oils and fats or organic residue before the formation of the above.

The silica coating layer 6 is formed by coating silica sol on the metal base 1 and baking the silica sol, and its film thickness is set in the range of 0.1 to 1.0 μm. There is.

As the phosphor emitting layer 3, a phosphor such as zinc sulfide dispersed in enamel is used, and the film thickness of the phosphor emitting layer 3 is set to about 40 to 60 μm .

The transparent protective layer 4 is made of enamel or polymer and its thickness is set to about 20 to 30 μm .

The transparent conductive film 5 is formed, for example, by depositing or sputtering an ITO film (indium oxide with tin added) or the like. The electrode extraction position provided on the transparent conductive film 5 is arbitrarily selected. To be done.

Although not shown, the transparent conductive film 5
A transparent protective layer made of a polymer can be further provided on the surface of the element for the purpose of insulating the element from the outside and protecting the element. In this case, the material polymer of the transparent protective layer is polyethylene or polyvinyl chloride. , Polyvinylidene chloride, polyvinylidene fluoride, polystyrene, polyvinyl alcohol, acrylic resin, cyanoethyl cellulose, cyanoethyl pullulan, cyanoethyl poval, cyanoethyl saccharose, cyanoethyl sorbitol, cyanoethyl sucrose and the like can be used.

Next, a method of manufacturing the inorganic dispersion type light emitting device of the present invention will be described.

First, a metal base 1 is prepared, and this metal base is
A silica coating layer 6 is formed on 1.

The silica coating layer 6 is formed by applying silica sol on the metal base 1 and firing it.

It is important that the silica coating layer 6 is fired in a nitrogen gas atmosphere. When firing is performed in the air, blackening occurs between the metal base 1 and the silica coating layer 6. An oxide film is generated, and light reflection tends to be significantly reduced, so that the metallic glossy surface of the metal base 1 cannot function as a reflecting surface, which is not preferable.

The thickness of the silica coating layer 6 is preferably in the range of 0.1 to 1.0 μm as described above,
If the thickness is less than 0.1 μm , the function as a passivation layer for preventing ion diffusion is insufficient, and blue or yellow coloring, which is considered as diffusion of iron ions or chromium ions, is generated in the phosphor light emitting layer 3 during firing of the phosphor layer. , The transparency of the binder of the phosphor light emitting layer 3 tends to decrease, and
If it exceeds 0 μm , it is necessary to repeat coating and firing many times, which is not preferable because productivity is poor and film peeling easily occurs when the number of times is extremely increased.

Here, when the silica coating layer 6 is formed by coating and baking silica sol, a film thickness of about 0.5 μm at most can be obtained by coating and baking once, but coating and baking silica sol. The silica coating layer 6 having a desired thickness can be formed several times, for example, 3 to 5 times. When the coating and firing are repeated several times, the iron ions of the metal base 1 are It is possible to form the silica coating layer 6 having a further excellent effect as a diffusion prevention layer.

Next, enamel glaze in which the phosphor is dispersed is applied on the silica coating layer 6 and dried, pre-baked, and baked to form the phosphor light-emitting layer 3.

Next, a transparent protective layer 4 is formed by applying enamel glaze on the phosphor light emitting layer 3 and drying, pre-baking and baking.

Further, an ITO film or the like is vapor-deposited or sputtered on the transparent protective layer 4 to form a transparent conductive film 5, and electrodes are formed at appropriate places on the transparent conductive film 5 and the metal base 1.

Further, if necessary, the transparent conductive film 5
By forming a transparent protective layer (not shown) made of a polymer on the above, the inorganic dispersion type light emitting device of the present invention, which is intended to be insulated from the outside and protect the device, can be completed.

In the thus obtained inorganic dispersion type light emitting device of the present invention, a voltage is applied from the power source to the electrodes formed on the metal base 1 and the transparent conductive film 5 through the lead wire or the like, whereby the phosphor light emitting layer 3 is applied. An electric field is generated and the phosphor emits light.

The inorganic dispersion type light emitting device of the present invention thus obtained and having the structure shown in FIG. 1 has a film thickness of 0.1 μm instead of the conventional insulating reflective layer having a film thickness of 30 μm or more. Since the silica coating layer 6 having a thickness of 1 to 1.0 μm is used, it is possible to eliminate the electric field loss caused by the insulating reflection layer and increase the electric field applied to the phosphor light emitting layer 3 by 1.4 to 1.5 times. Is possible.

The silica coating layer 6 has a thickness of 1 μm.
Even if it is as thin as the following, not only can the diffusion of iron ions, chromium ions, etc. from the metal base 1 to the phosphor emission layer 3 be sufficiently prevented, but also as a buffer layer that helps the adhesion between the metal base 1 and the phosphor emission layer 3. The phosphor emitting layer 3
Almost no trouble such as peeling can be eliminated.

Therefore, in the inorganic dispersion type light emitting device of the present invention, the silica coating layer can sufficiently protect the phosphor, and can sufficiently compensate the adhesion between the phosphor light emitting layer and the metal base and the brightness, so that the brightness is high. It exhibits the desirable characteristics that there is little unevenness in light emission and that it has excellent withstand voltage.

The constitution and effects of the present invention will be described in more detail below with reference to test examples.

[Test Example] Preparation of Metal Base Material (Core Material) As a metal base material, a stainless steel plate having a thickness of 1.0 mm and having its surface thoroughly washed was prepared.

Formation of silica coating layer As a silica sol, a sol prepared by hydrolysis of tetraethoxysilane is prepared, which is dipped on a stainless steel plate and fired to obtain a coating film. The so-called sol-gel method is used to form the silica coating layer. did.

Regarding the synthesis of silica sol, Yamamoto and Kamiya et al., "Study on the properties of coating film using metal alkoxide", Journal of Ceramic Society, 90, [6], 19
82, p52 to p57.

That is, first, a hydrolysis solution having the following composition ratio was prepared .

Tetraethoxysilane Si (OC ₂ H ₅ ) ₄ 0.40 mol ethanol C ₂ H ₅ OH 2.45 mol water H ₂ O 2.90 mol hydrochloric acid HCl 0.09 mol After mixing the above hydrolysis solution, The mixture was stirred at room temperature for 2 hours to obtain a silica sol solution.

Next, the operation of immersing the stainless steel plate in the above silica sol solution, pulling it up at a speed of 2.5 mm / sec, and immediately firing it in a 300 ° C. oven in a nitrogen gas atmosphere for 30 minutes was repeated 5 times. A silica coating layer having a film thickness of 1 μm was formed.

Formation of Phosphor Emitting Layer A phosphor emitting layer forming solution having the following composition was prepared.

Phosphor Silvania 729 42.0 g Low-melting glass TOSHIBA GLASS GSP220A524 18.0 g Dispersion medium α-Terpineol 19.0 g Binder polymer DuPont Elbasite 2045 0.2 g After stirring and mixing the above solution, The stainless steel sheet with the silica coating layer formed thereon is dipped, pulled up at a speed of 0.2 m / sec, naturally dried for 1 hour, baked in a nitrogen gas atmosphere at 380 ° C. for 10 minutes, and then the temperature of the oven. By raising the temperature to 680 ° C. and baking for 10 minutes,
A phosphor light emitting layer having a film thickness of 40 μm was formed.

Formation of Transparent Protective Layer A transparent protective layer forming solution having the following composition was prepared.

Low melting point glass GSP220A524 60.0 g manufactured by Toshiba Glass Co., Ltd. Dispersion medium α-terpineol 28.0 g Binder polymer Elponsite 2045 0.3 g manufactured by DuPont After stirring and mixing the above solution, the above phosphor emitting layer was formed on it. The stainless steel plate is dipped, pulled up at a speed of 0.2 m / sec, naturally dried for 1 hour, baked in an oven at 380 ° C for 10 minutes in a nitrogen gas atmosphere, and then the temperature of the oven is raised to 680 ° C for 10 minutes. By firing for a minute,
A transparent protective layer having a film thickness of 30 μm was formed.

Formation of transparent conductive film An ITO film was formed on the phosphor light emitting layer by a magnetro sputtering method under the following conditions.

Baking conditions: 200 ° C., 1 hour Sputtering time: 20 minutes Atmosphere (Ar) flow rate: 20 CCM Degree of vacuum: 1 × 10 ⁻⁸ Torr (1.3 × 10 ⁻⁶ Pa) Electrode formation Peel off the electrode formation part Then, an electrode was provided on a part of the core material, and an enameled wire was wound around the ITO film to form a simple electrode, thereby completing the inorganic dispersion type light emitting device of the present invention.

On the other hand, for comparison, instead of the silica coating layer, a film thickness of 3 having the same composition as the transparent protective layer was used.
A conventional inorganic dispersion type light emitting device was obtained by forming an insulating reflection layer of 0 μm .

When an AC electric field was applied between the electrode on the ITO film and the electrode on the metal base in these two types of inorganic dispersion type light emitting elements, the conventional inorganic dispersion type light emitting element was found to be 100 V and 400 Hz. The maximum was 20 cd / m ² , whereas the maximum amount of the inorganic dispersion-type light emitting device of the present invention was 3
A high emission luminance of 0 cd / m ^{2, which} is about 1.5 times higher, was obtained, and there was no deterioration of the phosphor, which was highly reliable.

[0059]

As described above, according to the present invention, an inorganic dispersion type light emitting device can be manufactured more efficiently than before, and moreover, the inorganic dispersion type light emitting device of the present invention is
Since it has high reliability in high emission brightness, uneven emission, and withstand voltage, it can be widely used, for example, as a pointer for automobile instruments and as a decoration for show windows.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view showing an embodiment of an inorganic dispersion type light emitting device of the present invention.

FIG. 2 is a sectional explanatory view showing an example of a conventional inorganic dispersion type light emitting device.

FIG. 3 is an enlarged cross-sectional view of a phosphor light emitting layer portion in FIG.

FIG. 4 is a cross-sectional explanatory view showing another example of a conventional inorganic dispersion type light emitting device.

[Explanation of symbols]

1 metal substrate 2 Insulating reflection layer (conventional example) 3 Phosphor emission layer 4 Transparent protective layer 5 Transparent conductive film 6 Silica coating layer

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-97397 (JP, A) JP-A-4-22095 (JP, A) JP-A-1-309292 (JP, A) Actual development Sho-59- 77795 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05B 33/00-33/28

Claims (2)

(57) [Claims] 1. A silica coating layer, a phosphor light emitting layer in which a phosphor is dispersed in a enamel, a transparent protective layer and a transparent conductive film are sequentially formed on the surface of the metal base, and the metal base and the transparent conductive film are formed. Inorganic dispersion type luminescence in which and are electrically connected
In the device, the thickness of the silica coating layer is 0.1 to 1 μm.
of the silica coating layer and the metal substrate
An inorganic dispersed light-emitting device, characterized in that the metallic glossy surface between them is used as a reflective film . 2. A silica sol is applied to the surface of a metal base,
The thickness of the silica coating layer is reduced to 0. by firing in a nitrogen gas atmosphere.
A method for manufacturing an inorganic dispersion type light emitting device, which comprises sequentially forming a phosphor light emitting layer, a transparent protective layer and a transparent conductive film on the silica coating layer after forming a thin film having a thickness of 1 to 1 μm.