JP3053548B2 - Electric field discharge type flat fluorescent lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat fluorescent lamp used as a backlight source of a liquid crystal display employed as a display unit of a portable computer, a portable TV set, and the like. The present invention relates to a configuration of an electric field discharge type flat fluorescent lamp.

[0002]

2. Description of the Related Art As a structure of a conventional flat fluorescent lamp of this type, there is one disclosed in Japanese Patent Application Laid-Open No. Hei 6-176736 (Japanese Patent Application No. 4-351732) filed by the same applicant. As shown in FIG. 2, reference numeral 90 denotes electrodes 93 and 94 laid on opposite surfaces of two glass substrates 91 and 92, respectively.

At this time, the glass substrates 91, 92
For example, the electrode 93 laid on the glass substrate 91 is a transparent and conductive member such as ITO because at least one side, for example, the glass substrate 91 side cannot take out light unless it has a light emitting surface. It is formed and made transparent. When light emission is not required on the other glass substrate 92 side, the electrodes 94 laid on the glass substrate 92 are formed by aluminum evaporation or the like and have a reflection function.

[0004] A dielectric layer 95 is provided on the surface of each of the electrodes 93 and 94 by firing low-melting glass, and a phosphor layer 96 is provided on the surface of the dielectric layer 95.
These two glass substrates 91 and 92 are heat-sealed at their peripheral edges with a glass frame 97 to form a flat fluorescent lamp 90. At this time, a sealing material 98 made of low-melting glass is used for the two glass substrates 91 and 92 and the glass frame 97 in order to reduce the heating temperature when performing sealing.

[0005]

However, in the structure of the above-described conventional flat fluorescent lamp 90, even when the sealing material 98 is used, the two glass substrates 91 and 9 are used.
2 is sealed by the glass frame 97, so that the low-melting glass on which the dielectric layer 95 is formed is softened. In this case, the phosphor provided on the surface of the dielectric layer 95 is softened. Layer 96 is taken into the low melting glass and solidifies,
As a result, the efficiency of converting ultraviolet light into visible light is reduced, and a problem arises in that a bright flat fluorescent lamp 90 cannot be obtained.

[0006]

According to the present invention, as a specific means for solving the above-mentioned conventional problems, at least one of the two glass substrates facing each other has at least one transparent surface. An electrode is laid, a dielectric layer of low-melting glass and a phosphor layer are sequentially provided on the electrode, and sealing is performed by heating at the periphery of the two glass substrates. In the flat fluorescent lamp, a thin film formed by a member having a melting point higher than a heating temperature when sealing the two glass substrates and having a dielectric property is provided between the dielectric layer and the phosphor layer. The object of the present invention is to solve the problem by providing an electric field discharge type flat fluorescent lamp characterized in that the barrier layer is provided.

[0007]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. 1 shows a flat fluorescent lamp according to the present invention. The flat fluorescent lamp 1 has electrodes 4 on opposite surfaces of two glass substrates 2 and 3 facing each other.
5 are laid, and the respective electrodes 4, 5
The dielectric layer 6 and the phosphor layer 7 made of low melting point glass
Is formed as in the conventional example.

Here, in the present invention, both glass substrates 2,
In both cases, a barrier layer 8 is provided between the dielectric layer 6 and the phosphor layer 7, and the procedure will be described below in the order of steps. In this embodiment, an example of the flat fluorescent lamp 1 having only one substrate 2 as a light emitting surface will be described.

First, an ITO transparent electrode 4 is laid on one surface of one glass substrate 2 by a film forming means such as sputtering, and an appropriate film forming means such as sputtering or vacuum deposition is formed on the other glass substrate 3. Thus, an aluminum electrode 5 is laid so as to have a reflection function.

On a surface of the electrode 4 of the one glass substrate 2, a paste having a required viscosity by adding a solvent and an organic component to a low-melting glass powder having a softening point of 485 ° C. is screen-printed, then dried and calcined. By performing the main baking, the above-mentioned solvent and organic components are removed, and a dielectric layer 6 made of low-melting glass having a thickness of 20 μm is formed.

Further, a barrier layer 8 having a thickness of 3000 to 3500 ° is formed on the surface of the dielectric layer 6 by sputtering SiO _2.
Is formed on the surface of the barrier layer 8 to form a phosphor layer 7 of a three-wavelength phosphor with a thickness of 15 μm. In addition, as a member for forming the barrier layer 8, the aforementioned Si
Not limited to O ₂ , for example, MgO, Al ₂ O ₃ , Ta
Any material such as ₂ O ₅ may be used as long as it is dielectric and does not soften by heating in a sealing step performed later.

On the surface of the electrode 5 of the other glass substrate 3, a dielectric layer 6 is formed to a thickness of 250 μm by a similar means, and a barrier layer 8 is formed to a thickness of 3000 to 3500 °. Layer 6 is formed to a thickness of 40 μm. At this time, the difference between the thickness of the dielectric layer 6 and the thickness of the phosphor layer 7 formed on the one glass substrate 2 and the other glass substrate 3 is that only one glass substrate 2 side has a light emitting surface. This is because the light extraction efficiency is improved by setting the transmittance on the light emitting surface side high.

The above-described extraction efficiency will be described in more detail. In the dielectric layer 6, the thickness of the electrode 4,
Because it is to determine the discharge impedance between 5
A predetermined thickness is required. On the other hand, since the transmittance increases as the thickness of the dielectric layer 6 decreases on the glass substrate 2 side, the dielectric layer 6 is formed to the minimum necessary thickness on the glass substrate 2 side. Is provided on the glass substrate 3 side to secure required discharge impedance.

In the phosphor layer 7, the light emission amount tends to be improved by increasing the thickness in a certain range, but the transmittance tends to be significantly reduced. Therefore, in the flat fluorescent lamp 1 in which only one glass substrate 2 is used as a light emitting surface as in this embodiment, the thickness of the phosphor layer 7 formed on one glass substrate 2 and the other glass substrate When the thickness of the phosphor layer 7 formed in No. 3 is set to an appropriate ratio, the maximum light emission amount can be obtained. In this embodiment, the thickness is determined based on this.

One substrate 2 and the other substrate 3 on which the dielectric layer 6, the barrier layer 8, and the phosphor layer 7 are respectively formed as described above are opposed to each other, and are sealed by the glass frame 9. . At this time, a low-melting glass having a softening point of 430 ° C. is applied to the joint between the substrates 2 and 3 and the glass frame 9 with the sealing material 9 a.
The sealing is performed by heating at 510 ° C., and the flat fluorescent lamp 1 is completed.

Here, comparing the flat fluorescent lamp 1 according to the present invention with the conventional flat fluorescent lamp in terms of luminance, the conventional flat fluorescent lamp has 1000 nt, whereas the flat fluorescent lamp of the present invention has 1000 nt. In the fluorescent lamp 1, a luminance improvement of 4000 nt, which is four times higher, is recognized. This is because a part of the phosphor layer 7 is taken into the softened dielectric layer 6 in the heating step at the time of sealing. 8 is prevented.

At the time of the above-mentioned lighting, the chromaticity of the conventional example is x = 0.231 and y = 0.298. Whereas, in the flat fluorescent lamp 1 of the present invention, x =
0.344, y = 0.354, which is almost pure white. For example, the color rendering property when used as a backlight light source of a color liquid crystal display device is also improved. Guessed.

[0018]

As described above, according to the present invention, between the dielectric layer and the phosphor layer, the melting point higher than the heating temperature at the time of sealing two glass substrates and the dielectric layer are used. With the electric field discharge type flat fluorescent lamp provided with a thin film barrier layer made of a material having a property, the dielectric layer is softened by heating during sealing, and the phosphor layer is taken in and solidified. The light emission is prevented from being caused by the barrier layer, and thereby the brightness of the flat fluorescent lamp is remarkably improved. It has the effect that it has. Further, the provision of the barrier layer has an effect of improving the color rendering of the flat fluorescent lamp.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an electric field discharge type flat fluorescent lamp according to the present invention.

FIG. 2 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Flat fluorescent lamp 2 ... One glass substrate 3 ... The other glass substrate 4, 5 ... Electrode 6 ... Dielectric layer 7 ... Phosphor layer 8 ... Barrier layer 9 ... Glass frame 9a …… Sealant

Claims (1)

(57) [Claims] An electrode, at least one of which is transparent, is laid on a surface of each of two glass substrates facing each other, and a dielectric layer made of low-melting glass, a phosphor layer and Are sequentially provided, and in the electric field discharge type flat fluorescent lamp in which the sealing by heating is performed at the peripheral edges of the two glass substrates, the two substrates are interposed between the dielectric layer and the phosphor layer. An electric field discharge type flat fluorescent lamp characterized in that a thin-film-like barrier layer made of a member having a dielectric property and having a melting point higher than the heating temperature at the time of sealing the glass substrate is provided.