JP2919681B2 - 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 structure.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays have been widely used as image display devices. In recent years, there has been a strong demand for color and large-sized liquid crystal displays.
It is common practice for liquid crystal displays to use a backlight to enhance visibility. As this kind of backlight, there is a flat fluorescent lamp,
As the size of the liquid crystal display increases, the thickness of the glass plate of the flat fluorescent lamp needs to be increased to ensure sufficient pressure resistance. For this reason, the size of the flat fluorescent lamp itself becomes large, and it is unavoidable to reduce the weight and size of the device.

As one of the measures, ITEJ Tec
hnical Report Vol12. No15
(Issued on March 25, 1988), pages 49 to 54. This is a structure as shown in FIG. 5. By providing a pressure-resistant spacer 3 between the front glass 1 and the rear glass 2, it is difficult to break even if the thickness of the front glass 1 and the rear glass 2 is reduced. A flat fluorescent lamp can be provided.

[0004] However, simply providing a spacer requires
Because the shadow of the spacer will be reflected on the light emitting surface,
A technique for reducing uneven light emission by applying a phosphor 4 on the side surface of the spacer 3 (see FIG. 6) or providing a diffusion plate 5 (see FIG. 5) on the light emitting surface is described in the same document. Have been.

[0005]

However, the application of the phosphor to the spacer increases the number of work steps and leads to an increase in cost, and the diffusion plate lowers the brightness of the entire flat fluorescent lamp, which is desired. There is a problem that brightness cannot be obtained.

[0006]

According to the present invention, a sealed container is formed by a first glass substrate having a phosphor layer on an inner surface and a second glass substrate having a phosphor layer on an inner surface. In flat fluorescent lamps
A spacer for reinforcing pressure resistance is provided between the first glass substrate and the second glass substrate, and a recess having a substantially V-shaped cross section is formed on the surface of the first glass substrate in the spacer portion. A flat fluorescent lamp characterized in that it has a substantially Y-shaped cross section with the concave portion.

[0007]

According to the structure described above, light is collected in the concave portion having a substantially V-shaped cross section, and the shadow of the spacer for reinforcing the pressure resistance does not appear on the light emitting surface.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. First, FIG. 1 shows the appearance of a flat fluorescent lamp according to the present invention. In the figure, 6 is a front glass panel as a first glass substrate, 7 is a rear glass panel as a second glass substrate, 8 is a chip tube, and 9 and 9 are lead terminals. Reference numerals 10 and 10 denote recesses having a substantially V-shaped cross section formed on the surface of the front glass panel.

Next, FIG. 2 shows a sectional side view of a main part of the flat fluorescent lamp. In the figure, reference numeral 11 denotes a first rib for reinforcing pressure resistance which is planted from the inner surface of the front glass panel 6, and the first rib 11 is formed integrally with the front glass panel 6. Reference numeral 12 denotes a second rib for pressure-resistance reinforcement planted on the inner surface of the rear glass panel 7. The second rib 12 is formed integrally with the rear glass panel 7. The first rib 11 and the second rib 12 form a spacer. Therefore, the concave portion 10 is formed on the surface of the front glass panel 6 on the front side of the first rib 11, and the concave portion 10 and the spacer have a substantially Y-shaped cross section. Further, phosphor layers 13 and 13 are formed on the inner surfaces of the front glass panel 6 and the rear glass panel 7, respectively.

Next, the operation of the concave portion 10 having a substantially V-shaped cross section will be described in detail with reference to FIGS. In the flat fluorescent lamp, the phosphor layer 13 on the inner surface of the rear glass panel 7 is a main light source. Now, light emitted at points A1 and A2 in FIG.
It refracts at 0 and reaches point A3. Similarly, light emitted at the points B1 and B2 is refracted at the concave portion 10 of the front glass panel 6 to reach the point B3, and light emitted at points C1 and C2 is refracted at the concave portion 10 of the front glass panel 6 to be C3. To the point. Since the light emitting source does not exist in the spacer portion formed by the first rib 11 and the second rib 12, when the fluorescent lamp is viewed from the front side, the spacer portion appears as a shadow. By properly selecting the inclination angle θ, the plate thickness t of the concave portion 10, and the width d of the spacer portion formed by the first rib 11 and the second rib 12, when the fluorescent lamp is viewed from the front, the spacer portion becomes You can avoid shadows.

Since the path of light is reversible, an optical path when light is emitted from the front side of the fluorescent lamp will be considered. In FIG. 4, it is assumed that light emitted from points D1 and E1 reaches points D5 and E5 via points D4 and E4. The index of refraction is the ratio of the high speed va in air to the high speed vg in glass, which is about 1.5 for glass. Therefore,

[0012]

(Equation 1)

On the other hand, ΔD2E3D3 = θ ′ = ΔD4D2
Because P

[0014]

(Equation 2)

Also, since {RE3Q = 90} −θ, E3
Θ ′ + 90 ° + α + 90 ° −θ
= 180 °, so α = θ-θ '. E
The distance ds at which one light deviates from its original position is

[0016]

(Equation 3)

From equations (2) and (3),

[0018]

(Equation 4)

Calculating the relationship between θ, t, and ds from Equations 1 and 4,

[0020]

[Table 1]

## EQU1 ## This is θ = 45 °, t = 1.52
If it is set to mm, it means that light coming from directly above is shifted by 0.5 mm. Therefore, 2 × ds = 2 × 0.5 = 1 m
Spacers with a width of up to m will not be visible from directly above. In actuality, since it is more likely to be viewed from an oblique direction than from directly above, it is necessary to slightly increase the plate thickness t. When the plate thickness t increases, the distance ds increases accordingly, and a margin can be provided for the actual width d of the spacer portion, and the angle at which the shadow of the spacer portion is not seen when viewed from an oblique direction, that is, the viewing angle Can be set large.

The dimensions of each part of the fluorescent lamp in this embodiment will be described below.

[0023]

[Table 2]

In the present embodiment, the inclination angle θ of the inclined surface in the concave portion 10 is set to 60 ° and the plate thickness t is set to 1.17 mm. The spacers formed by the first ribs 11 and the second ribs 12 are originally at least 2.5 m.
The front glass panel and the rear glass panel, which required a thickness of m, could be reduced to about 1 mm.

[0025]

As described above, according to the present invention, a sealed container is formed by a first glass substrate having a phosphor layer on the inner surface and a second glass substrate having a phosphor layer on the inner surface. The flat fluorescent lamp comprises a spacer for reinforcing pressure resistance between the first glass substrate and the second glass substrate, and a concave portion having a substantially V-shaped cross section is formed on the surface of the first glass substrate in the spacer portion. Since the spacer portion and the concave portion have a substantially Y-shaped cross section, the spacer portion provided thereunder does not appear as a shadow due to the refraction of light in the concave portion. Therefore, the first glass substrate and the second glass substrate can be thinned to obtain a light and small flat fluorescent lamp.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a cold cathode flat fluorescent lamp of the present invention.

FIG. 2 is a side sectional view showing a main part of the cold cathode flat fluorescent lamp of the present invention.

FIG. 3 is a diagram illustrating the principle of the present invention.

FIG. 4 is a diagram illustrating the principle of the present invention.

FIG. 5 is a perspective view showing the structure of a conventional cold cathode flat fluorescent lamp.

FIG. 6 is a side sectional view showing a main part of a conventional cold cathode flat fluorescent lamp.

[Explanation of symbols]

 Reference Signs List 6 front glass panel 7 rear glass panel 8 chip tube 9 lead terminal 10 concave portion 11 first rib 12 second rib 13 phosphor layer

Claims (1)

(57) [Claims] 1. A flat fluorescent lamp comprising a sealed container formed by a first glass substrate having a phosphor layer on an inner surface and a second glass substrate having a phosphor layer on an inner surface.
A spacer for reinforcing pressure resistance is provided between the first glass substrate and the second glass substrate, and a recess having a substantially V-shaped cross section is formed on the surface of the first glass substrate in the spacer portion. A flat fluorescent lamp characterized in that it has a substantially Y-shaped cross section with a concave portion.