JPH08162069A - Flat type fluorescent lamp - Google Patents

Abstract

PURPOSE: To provide a flat type fluorescent lamp excellent in luminous efficiency by forming an emitting surface-side phosphor layer on a transparent electrode into a specified thickness thinner than the thickness of a reflecting surface-side phosphor layer on a reflecting electrode layer. CONSTITUTION: A transparent electrode layer 3 such as ITO is provided on an emission-side glass substrate 2, and an emitting surface-side phosphor layer 5 is formed thereon through a transparent dielectric layer 4. On the other hand, a reflecting electrode layer 8 is provided on a reflecting-side glass substrate 6 by aluminum evaporation, and a reflecting surface-side phosphor layer 8 is formed thereon through a transparent dielectric layer 4. The both are sealed opposite to each other through a sealing material 9, and a rare gas and mercury are sealed into the formed discharge chamber 1a. In the thus-obtained flat fluorescent lamp 1, the thickness t1 of the emitting surface-side phosphor layer 5 is set to 5-10μm, and the thickness t2 of the reflecting surface-side phosphor layer 8 is set to 5-40μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp, and more particularly, to a rectangular light emitting surface suitable for use as a backlight of a liquid crystal display device used as a display screen of a portable television receiver. The present invention relates to a flat fluorescent lamp having a flat surface.

[0002]

2. Description of the Related Art FIG. 4 shows the structure of a conventional flat fluorescent lamp 90 of this type.
When 0 is used for the backlight of the liquid crystal display device described above, for example, one of them is the light emitting surface glass substrate 9
The one and the other are formed as the reflecting surface glass substrate 92.

On the surface of the light-emitting surface glass substrate 91 facing the reflection surface glass substrate 92, a transparent electrode 93 made transparent by using a transparent conductive member such as ITO, and a transparent dielectric made of silicon oxide or the like. A body layer 94 and a phosphor layer 95 are formed on the upper surface of the body layer 94 by a dipping method or the like so as to have a film thickness of about 15 μm. On the other hand, a reflection electrode 96 is formed on the opposite surface of the reflection surface glass substrate 92 by an aluminum vapor deposition film or the like. Is deposited.

The light emitting surface glass substrate 91 and the reflection surface glass substrate 92 formed as described above are sealed at their peripheral edges with a sealing material 97 such as frit glass to form a discharge chamber 90a, and the discharge chamber 90a is formed. A flat gas fluorescent lamp 90 is completed by enclosing a rare gas, mercury, etc. therein.

With the above structure, when the flat fluorescent lamp 90 is turned on, the light emitted from the phosphor layer 95 on the light emitting surface glass substrate 91 side passes through the transparent dielectric layer 94 and the transparent electrode 93. The light emitted from the phosphor layer 95 on the reflective surface glass substrate 92 side reaches a part of the phosphor layer 95 on the light emitting surface glass substrate 91 side directly and is partially reflected by the reflective electrode 96. After the light emitting surface glass substrate 91
It reaches the phosphor layer 95 on the side, whereby the emitted light to the outside is enhanced.

[0006]

In the flat fluorescent lamp 90 of this type, the flat fluorescent lamp 90 is often lit by a small-capacity power source such as a battery. Therefore, the power consumption is reduced as much as possible and the usable time is extended. Therefore, further improvement of luminous efficiency is required. However, with the current configuration, it is difficult to further improve the luminous efficiency, and there arises a problem that the demand of the market cannot be met, and a solution to this problem has been a problem.

[0007]

The present invention is, as a concrete means for solving the above-mentioned conventional problems, an electrode, a dielectric layer, and an electrode, a dielectric layer, on the opposite surfaces of two glass substrates facing each other.
A flat fluorescent lamp in which a phosphor layer is formed, and the electrode and the dielectric layer on one side are translucent, and the other electrode is reflective, and In a flat fluorescent lamp having a light emitting surface on one side and a reflecting surface on the other side, the phosphor layer on the light emitting surface side has a film thickness of 5
By providing the flat fluorescent lamp, the thickness of the phosphor layer on the reflecting surface side is set to 25 to 40 μm, thereby further improving the luminous efficiency. It solves the problem.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail based on an embodiment shown in the drawings. Reference numeral 1 in FIG. 1 is a flat fluorescent lamp according to the present invention.
Has a light emitting surface and a reflecting surface defined, and a transparent electrode layer 3 made of ITO or the like is formed on the opposite surface on the light emitting side glass substrate 2 side, and the transparent electrode layer 3 is covered to form a transparent dielectric layer. The body layer 4 is formed, and the light emitting side phosphor layer 5 is further formed.

A reflective electrode layer 7 is formed on the opposite surface of the other reflective side glass substrate 6 by vapor deposition of aluminum or the like, and the reflective electrode layer 7 is covered so that it is similar to that of the light emitting side glass substrate 2. The transparent dielectric layer 3 is formed, and the reflection side phosphor layer 8 is further formed on the upper surface. A reference numeral 9 in the drawing is a sealing material made of frit glass for forming the discharge chamber 1a by the light emitting side glass substrate 2 and the reflection side glass substrate 6.

Here, FIG. 2 shows the result of the study by the inventor for making the present invention. The light emitting side phosphor layer 5 emits light by being excited from the back side, and in addition, it reflects. Since the light from the side phosphor layer 8 is transmitted, the transmission brightness TB and the transmittance TT are measured with respect to the film thickness t in FIG. Further, since the reflection side phosphor layer 8 is excited from the front side, the reflection brightness TR is measured and each result is displayed.

According to the above measurement results, the transmission brightness TB of the light emitting side phosphor layer 5 tends to decrease as the film thickness t increases, and at the same time the transmittance TT also increases the film thickness t1. It will be lowered. Therefore, it can be estimated that forming the film thickness t1 in the light emitting side phosphor layer 5 as thin as possible is effective as a means for improving the brightness of the flat fluorescent lamp 1.

On the other hand, the reflection brightness TR of the reflection side phosphor layer 8 tends to improve as the film thickness t2 increases. However, when the film thickness t2 is 35 to 40 μm, the brightness is saturated,
It has been clarified that even if the film thickness t2 is further increased, the brightness is not further improved. Therefore, the reflection side phosphor layer 8 has a thickness t2 within the above range, that is, 40.
It can be estimated that increasing the film thickness t2 in the range up to μm is effective as a means for improving the brightness.

FIG. 3 shows the luminance characteristics of the prototype flat fluorescent lamp 1 based on the above-mentioned examination results. In the prototype, the thickness t1 of the light emitting side phosphor layer 5 and the reflection side phosphor layer 8 are shown. Film thickness t2 of 8 μm, 18 μm, and 25 μm, respectively.
m and 35 μm were prepared, and these were combined with each other to form the flat fluorescent lamp 1, and the flat fluorescent lamp 1 was turned on to measure the luminance.

A curved line F8 in the figure shows the light emitting side phosphor layer 5 having a thickness of 8 μm.
Brightness characteristics obtained when the thickness of the reflection side phosphor layer 8 is fixed at m and the curve F18 is the same when the emission side phosphor layer 5 is 18 μm and the curve F25 is the emission side phosphor layer. 5 is 25 μm, the curve F35 shows that the emission side phosphor layer 5 is 3
The luminance characteristics at 5 μm are shown respectively.

When comparing the above curves,
When a film thickness of 18 μm, which is generally used as a standard value of the film thickness of the phosphor layer in this type of fluorescent lamp, is formed on both the light emitting side phosphor layer 5 and the reflection side phosphor layer 8, The luminance value is shown as 100 with a reference value P, and this reference value P is the brightness of a conventional flat fluorescent lamp of this type.

Also in this prototype, the light emitting side phosphor layer 5 is formed as thin as possible, and the reflection side phosphor layer 8 is 40 μm.
It has been confirmed that it is effective to increase the brightness in the range up to the above range. Specifically, when the emission side phosphor layer 5 is formed to have a thickness of 8 μm and the reflection side phosphor layer 8 is formed to have a thickness of 35 μm, it is approximately 1 It was clarified that the luminance can be improved by 3 times (see the curve F8).

Here, a desired film thickness t is applied to both phosphor layers 5 and 8.
A means for obtaining 1 and t2 will be described. According to the conventional dipping method, the film thickness obtained is limited to 15 to 18 μm and the desired film thickness cannot be obtained. Therefore, in the present invention, instead of the above-mentioned dipping method, a screen printing method is adopted for forming both phosphor layers 5 and 8 to enable adjustment of the film thickness.

At this time, first, the powder of the three-wavelength (R, G, B) phosphor is mixed with an acrylic ester polymer binder and an aromatic or ester solvent to prepare a paste ink, which is prepared for screen printing. . After that, by printing on the glass substrates 2 and 6 by screen printing, drying,
By baking, the solvent and the binder are completely vaporized and decomposed, and the phosphor layers 5 and 8 are obtained.

Therefore, the basic film thickness of the phosphor layers 5 and 8 is determined by setting the film thickness of the silk screen at the time of screen printing to an appropriate value. The film thickness can be finely adjusted by appropriately adjusting the mixing ratio of the phosphor powder, the binder and the solvent, and the phosphor layers 5 and 8 having a desired film thickness can be obtained by these means.

[0020]

As described above, according to the present invention, the phosphor layer on the light emitting surface side has a film thickness of 5 to 10 μm, and the phosphor layer on the reflecting surface side has a film thickness of 25 to 40 μm. Since it is a flat fluorescent lamp, the light is directly output from only one phosphor layer side, and the light is output from the other one phosphor layer side through one phosphor layer. For this type of flat fluorescent lamp, in which each of the phosphor layers is given optimum conditions for improving the luminous efficiency,
As a result, the luminous efficiency can be improved, and an extremely excellent effect can be obtained in improving the performance of this type of flat fluorescent lamp.

Further, conventionally, a phosphor layer was formed by a dipping method, and it was impossible to obtain a desired value for the thickness of this phosphor layer, whereas it was formed by screen printing according to the present invention. By adjusting the film thickness at the time of printing and the mixing ratio of the binder to the phosphor powder, a desired film thickness can be freely obtained, and an excellent effect of facilitating the implementation is also exhibited.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a flat fluorescent lamp according to the present invention.

FIG. 2 is a graph showing characteristics of a phosphor layer.

FIG. 3 is a graph showing the relationship between the light output and the film thickness of the phosphor layer on the light emitting surface side and the reflection surface side.

FIG. 4 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1 ... Flat fluorescent lamp 1a ... Discharge chamber 2 ... Light emitting side glass substrate 3 ... Transparent electrode layer 4 ... Transparent dielectric layer 5 ... Light emitting side phosphor layer 6 ... Reflecting side glass substrate 7 ... Reflective electrode layer 8 ... Reflective side phosphor layer 9 ... Sealing material t1 ... Thickness of light emitting side phosphor layer t2 ... Thickness of reflective side phosphor layer

Claims (2)

[Claims] 1. A flat fluorescent lamp comprising electrodes, a dielectric layer, and a phosphor layer formed on the opposite surfaces of two glass substrates facing each other, and the electrode and the dielectric on one side. In the flat fluorescent lamp, the body layer is translucent, the other electrode is reflective, the surface on the one side is a light emitting surface, and the surface on the other side is a reflecting surface. The flat fluorescent lamp, wherein the phosphor layer on the light emitting surface side has a thickness of 5 to 10 μm, and the phosphor layer on the reflecting surface side has a thickness of 25 to 40 μm. 2. The phosphor layer is formed by screen printing, and a predetermined film thickness is obtained by adjusting a film thickness at the time of printing and a mixing ratio of the binder to the phosphor powder. The flat fluorescent lamp described.