JP2848469B2 - Flat fluorescent lamp - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flat fluorescent lamp used as a backlight for a viewfinder of a video camera, a liquid crystal display of a liquid crystal television, and the like.

(Prior Art) A liquid crystal display device requires a backlight for illuminating the liquid crystal display panel from the back, and the backlight is required to illuminate the liquid crystal display panel with uniform brightness over the whole.

Applicants have previously used a third light source to achieve a planar light source.
A flat fluorescent lamp as shown in the figure was proposed (Japanese Patent Laid-Open No. 60-189154).
issue).

In the flat fluorescent lamp, a front glass plate (9) and a rear glass plate (91) each having a phosphor (94) (95) coated on an inner surface thereof are sandwiched between frame-shaped side glass plates (92) and (93). The glass container is hermetically bonded and has a discharge chamber (99) inside.
After evacuating the discharge chamber (99) through the exhaust pipe (98), the discharge chamber (99) is filled with argon gas and mercury vapor. Further, inside the discharge chamber (99), a pair of electrodes (96) and (97) are arranged at both ends with the phosphors (94) and (95) interposed therebetween.

When a discharge is generated between the electrodes (96) and (97) by the application of the AC voltage, ultraviolet rays are emitted from the argon gas and mercury, and the ultraviolet rays excite the phosphor to generate visible rays.

(Problem to be Solved) In a video camera and a liquid crystal television, since a battery is used as a power supply, there is a limit to a power supply capacity that can be allocated as power consumption of the flat fluorescent lamp.
However, if the discharge current of the fluorescent lamp is reduced to reduce the power consumption, the light emission luminance is reduced and the function as a backlight is impaired.

To increase the light emission luminance, the current density in the discharge chamber (99) may be increased. However, if the discharge chamber (99) is further flattened, the electrodes (96) (97) become smaller accordingly. Inevitably, the electron emission area becomes smaller. As a result, the discharge current decreases, and the current density does not increase so much.

SUMMARY OF THE INVENTION An object of the present invention is to provide a flat fluorescent lamp capable of obtaining higher luminance than before using limited power by devising the shape of the inside of a glass container.

Further, the present invention forms a space below the flat fluorescent lamp,
For example, it is an object of the present invention to provide a flat fluorescent lamp that can be attached to a substrate even if the substrate has projections such as electronic components and can contribute to miniaturization of electronic devices.

(Means for Solving the Problems) In a flat fluorescent lamp according to the present invention, phosphors (3) and (4) are provided on the inner surface of a flat glass container, and the phosphor is sandwiched inside the glass container. A pair of electrodes on both ends (5)
In the flat fluorescent lamp in which (6) is disposed opposite to each other, the glass container has two parallel electrode receiving chambers (81) and (82) formed at both ends to protrude downward, and the two electrode receiving chambers (81) and (82). The thin flat discharge chamber (8) is formed by raising the bottom wall so as to approach the upper wall of the lower wall in parallel with the upper wall to form a thin flat discharge chamber (8). A space (21) is formed between the lower wall surface of the chamber (8) and the front and rear directions and the lower side is open.

(Operation and Effect) According to the above-mentioned flat fluorescent lamp, with the dimensions and the applied voltage of both electrodes (5) and (6) and the applied voltage maintained at the same values as in the past,
The discharge chamber (8) can be formed in a flat space having a smaller thickness than that of the related art, so that the area of the cross section of the discharge chamber (8) perpendicular to the discharge direction becomes smaller than before. Therefore, even if the magnitude of the discharge current generated between both electrodes is the same as before,
The current density in the discharge chamber (8) increases. As a result, the light emission luminance increases.

Further, a space (21) is formed below the discharge chamber (8) between the electrode housing chambers (81) and (82) protruding below both ends,
Since this space is opened forward and backward and downward, it can be mounted from above the substrate on which the electronic component (23) is mounted, and not only can the space be used effectively, but also air can flow through the mounting space (21). Thus, the discharge chamber can also be cooled.

(Example) The example is intended to illustrate the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof.

As shown in FIGS. 1 and 2, the flat type fluorescent lamp has a flat front glass plate (1) and a dish-shaped rear glass plate (2) which are airtightly joined with frit glass or the like. A glass container is formed, and phosphors (3) and (4) are applied to the inner surfaces of the front glass plate (1) and the rear glass plate (2), respectively. The inside of the glass container is evacuated through an exhaust pipe (7), and is filled with argon gas and mercury vapor.

The rear glass plate (2) is formed so that both ends where the pair of electrodes (5) and (6) are to be arranged are deep, and the electrode accommodating chambers (81) and (82).
And the area where the phosphor (3) is applied is formed shallowly in the shape of a raised bottom parallel to the upper wall surface to provide the discharge chamber (8).

The pair of electrodes (5) and (6) to be disposed in the electrode storage chambers (81) and (82) are formed of, for example, an iron-nickel alloy, one of which is used as a cathode and the other as an anode. Lead plates (51) (61) on both ends of the electrodes (5) and (6)
Are fixed by welding, and the tips of the lead plates (51) and (61) are drawn out of the glass container.

The length L of the glass container is 32 mm, the width W is 22 mm, and the thickness H of the portion provided with the electrode housing chambers (81) and (82) is 5.5 mm. The height A of the electrodes 5 and 6 is 3 mm, the width B is 2 mm, and the length C is 16.3 mm.

On the lower surface of the glass container, two electrode chambers (81)
Between (82), a space (21) opened forward and backward and downward is formed.

One electrode (5) is a cathode on the lead plates (51) and (61).
A drive circuit (not shown) is connected so that the other electrode (6) becomes an anode. The electrode (5) as a cathode has zero potential, and the electrode (6) as an anode has, for example, 500 V for 8 μsec. A pulse voltage with a period of 15.73 KHz is applied.

While maintaining the electrode shape and applied voltage at the predetermined values,
Experiments were conducted to measure the brightness of various flat fluorescent lamps with the thickness D of the discharge chamber (8) shown in FIG. 1 varied, and the following results were obtained. The luminance was measured at the center of the phosphor screen.

When the thickness D is 3.5 mm, the structure is the same as that of the conventional flat fluorescent lamp shown in FIG. 3, and the luminance in this case is 2985 nt.

On the other hand, as the structure of the flat fluorescent lamp according to the present invention, when the thickness D is formed to be 3.0 mm, the luminance is 3030 nt, and when the thickness D is formed to be 2.5 mm, the luminance is 3440 nt. It was confirmed that the luminance increased.

Therefore, according to the flat fluorescent lamp according to the present invention, a higher luminance than before can be obtained with the same power consumption as before, and the function as a backlight can be sufficiently achieved.

The description of the above embodiments is for the purpose of describing the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a flat fluorescent lamp according to the present invention,
FIG. 2 is an exploded perspective view of the flat fluorescent lamp, and FIG. 3 is a partially broken perspective view of the previous flat fluorescent lamp according to the proposal of the present applicant. (1) front glass plate, (2) rear glass plate (3) (4) phosphor, (5) (6) electrode (8) discharge chamber, (81) (82) electrode housing chamber

 ──────────────────────────────────────────────────の Continued on the front page (72) Hiroshi Takeo 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Eiichi Kotani 2--18 Keihanhondori, Moriguchi-shi, Osaka Inside Sanyo Electric Co., Ltd. (72) Inventor Masayuki Sawada 3816, Okubo, Takao-cho, Izumi-gun, Kagoshima 23 Inside Yamato Electronics Co., Ltd. (56) References JP-A-60-189154 (JP, A) JP-A-64-17374 (JP, A)

Claims (1)

(57) [Claims] 1. A phosphor (3) on an inner surface of a flat glass container.
In the flat fluorescent lamp in which (4) is provided and a pair of electrodes (5) and (6) are provided opposite to each other with the phosphor interposed therebetween inside the glass container, the glass container has two parallel lines at both ends. Electrode housings (81) and (82) are formed to protrude downward, and the lower wall between both electrode housings (81) and (82) is raised so as to approach the upper wall and rises high parallel to the upper wall like a bottom. To form a thin flat discharge chamber (8), and two electrode accommodating chambers (81).
A flat fluorescent lamp characterized by forming a space (21) open in the front-rear direction and below between the (82) and the lower wall surface of the discharge chamber (8).