JP2000323100A - Flat light source and liquid crystal display device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve lighting delay after dark shelf and starting ability at low temperature and to provide a light source with high efficiency and uniform luminance, by providing an auxiliary electrode close to one of discharge electrode and ensuring distance between external guiding portions by forming an electrode on a luminescent region side in the L shape. SOLUTION: A pair of discharge electrodes 4, 5 are provided inside a front plate of an airtight container 1. An auxiliary electrode 6 is provided close to a corner of the discharge electrode 5 in a substantially L shape. The surfaces of the discharge electrodes 4, 5 and the auxiliary electrode 6 are coated with a conductive layer by thick film printing. For driving this flat-plate-type light source, for example, rectangular wave voltage is impressed on the electrode 4, and rectangular wave voltage having phase shifted by a half period is impressed on the electrode 5. Thus, discharge occurs in a discharge space, ultraviolet radiation occurring with discharge excites phosphor to emit light, and the light is radiated outside through the front plate. The auxiliary electrode 6 is connected to the discharge electrode 4 so as to remain same potential via a high resistance, and when the voltages are impressed on the discharge electrodes 4, 5, initially, micro discharge occurs between the discharge electrode 5 and the auxiliary electrode 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat light source which emits light in a plane, and more particularly, to a display device such as a liquid crystal panel which requires a backlight, for example, a television, a game machine, a car navigation system and the like. OA equipment such as an information video equipment and a word processor, or a flat light source in a display system incorporating a light source.

[0002]

2. Description of the Related Art Liquid crystal panels are widely used for various information and image displays such as personal computers and televisions because of their thinness, lightness, and low power consumption. A backlight that supplies light from the back is required. The backlight generally used is mainly a combination of a small-diameter fluorescent lamp and an acrylic resin light guide, but a flat discharge lamp is also used.

FIG. 7 is a cross-sectional view of a conventional flat light source described in, for example, Japanese Patent Application Laid-Open No. Hei 9-115483. As shown in the figure, a translucent front plate 2 made of soda glass or the like.
And an insulating substrate 14 made of soda glass, ceramic, or the like.
The side plate 15 and the side plate 15 are integrally hermetically sealed with, for example, low-melting glass (not shown) to form a flat airtight container 1. A pair of discharge electrodes 4 and 5 parallel to each other are provided on the inner surface of the front plate 2 serving as a light emitting surface.
5 is covered with a dielectric layer 7. The phosphor 8 is coated on the inner surface of the insulating substrate 14 so that the airtight container 1
The discharge space 9 in the inside is filled with a mixed gas of mercury and a starting gas such as argon or neon-argon, or a rare gas such as xenon, krypton, helium, or neon.

[0004] The flat-type light source according to the present configuration includes a discharge electrode 4,
By applying a high-frequency voltage across the discharge space 5, a discharge is generated in the discharge space 9, and the ultraviolet light generated by the discharge causes the phosphor 8 to emit light.
Are excited to emit light. The light emitted by the phosphor is applied to the front panel 2
Is radiated to the outside. Reference numeral 16 denotes the direction of light emission.

[0005]

The conventional flat light source is
An auxiliary electrode may be provided in the vicinity of the discharge electrode in order to prevent lighting delay and to improve startability at low temperatures. In this case, when the main discharge electrode and the auxiliary electrode are linearly led out to the outside, the distance at the outside lead-out part becomes short, and there is a possibility that the lead wire is short-circuited and turned off in the soldering work. Further, there is a problem that a leakage current is generated and efficiency is reduced.

Further, as another method, there is a method in which an auxiliary electrode is provided on the frame side and the main electrode is made substantially L-shaped to increase the distance between the auxiliary discharge and the outside lead-out portion of the main discharge. In the corners of the mold, since the vertical electrode and the horizontal electrode having the same potential exist, there is a problem that the potential gradient in the vicinity is reduced, the brightness is reduced, and the brightness uniformity is deteriorated.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and it is possible to improve a lighting delay after being left in the dark and a startability at a low temperature with a simple structure, and to obtain a highly efficient and uniform luminance plate. It is to provide a mold light source.

[0008]

According to the present invention, a flat airtight container is provided by combining a light-transmitting front plate serving as a light emitting surface and a rear plate formed of a shallow dish-shaped container. And a pair of discharge electrodes serving as discharge main electrodes are provided on the inner surface of the front plate, and an auxiliary electrode is provided in the vicinity of one of the discharge electrodes, so that the light emitting region side electrode is substantially L-shaped. . When the discharge electrode is substantially L-shaped, an auxiliary electrode is provided near a corner of the substantially L-shape. further,
A dielectric layer is provided on the surface.

In the liquid crystal display device, the flat light source is used as a backlight.

[0010] Further, in the lighting device, illumination is performed using the flat light source.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing an embodiment of a flat light source according to the present invention. FIG. 1 is a plan view, and FIG.
FIG. 4 shows a cross-sectional view of the part A-A ′. As shown in the figure, a translucent front plate 2 made of, for example, soda glass or the like and a rear plate 3 of a shallow dish-shaped container made of soda glass, ceramics or the like are integrally made of, for example, low-melting glass (not shown). The container is hermetically sealed to form a flat airtight container 1. A pair of discharge electrodes 4 and 5 are provided inside the front plate 2, and an auxiliary electrode 6 is provided near a corner of the substantially L-shaped discharge electrode 5, and the discharge electrodes 4 and 5 and the auxiliary electrode 6 are provided. Is covered with a dielectric layer 7 provided by a thick film printing method or the like. Discharge electrode 4,
The external lead-out portion serving as the circuit connection portion of the auxiliary electrode 5 and the auxiliary electrode 6 is widened so that the soldering operation can be easily performed. A part of the auxiliary electrode 6 was exposed to the discharge space 9 via the dielectric layer 7. Phosphors 8 having different film thicknesses are respectively provided on the inner surface of front plate 2 and the inner surface of back plate 3.
The discharge space 9 in the airtight container 1 is filled with a rare gas such as argon or xenon, or a mixed gas containing xenon.

The driving method of the flat light source according to this embodiment is as follows.
For example, as shown in FIG.
A rectangular wave voltage V1 having a voltage of Vh is applied to the electrode 5, and 13 rectangular wave voltages V2 having a phase shift of half a cycle from 12 are applied to the electrode 5. By using such a driving method, a discharge is generated in the discharge space 9, and the fluorescent material 8 is generated by ultraviolet rays generated by the discharge.
Are excited to emit light, and light is emitted to the outside through the front plate 2.

The auxiliary electrode 6 is connected to the discharge electrode 4 via a high resistance so as to maintain the same potential.
At the initial stage of application of the rectangular wave voltage to the electrode 5, a slight discharge occurs between the discharge electrode 5 and the auxiliary electrode 6. When a normal discharge is performed between the discharge electrodes 4 and 5, the minute discharge between the discharge electrode 5 and the auxiliary electrode 6 is stopped.

In the above-mentioned flat type light source, the distance between the externally derived portions can be ensured by making the discharge electrodes near the auxiliary discharge substantially L-shaped, so that the auxiliary electrode and the main discharge electrode are short-circuited during the soldering operation. Is less likely to do so. Also,
By providing the auxiliary electrode in the vicinity of the substantially L-shaped corner of the discharge electrode, the electric charge in the substantially L-shaped corner having a small potential gradient can be easily moved, and the same brightness output as the peripheral part can be obtained. .

FIG. 4 shows another embodiment of the present invention, and is a plan view of a structure in which the auxiliary electrode 6 is on the light emitting region side. By making the auxiliary electrode 6 transparent conductive, the same light emitting area can be obtained with the same external shape.

FIG. 5 is a sectional view of a structure in which auxiliary electrodes 6 are embedded in the frame portions of the front plate 2 and the back plate 3. The pattern of the substantially L-shaped discharge electrode is angular. By incorporating the auxiliary electrode into the frame portions of the front plate and the rear plate, the outer shape can be reduced if the light emitting area is the same.

FIG. 6 shows still another embodiment of the present invention.
In the structure where the auxiliary electrode 6 is on the light emitting region side, the front plate 2
FIG. 4 is a plan view showing a structure in which auxiliary electrodes 6 are embedded in a frame portion of a rear plate 3. Also in this structure, the outer shape can be reduced if the light emitting area is the same.

When the flat light source of the present invention is used in, for example, an illuminating device, the problems of lighting delay and startability at low temperatures can be improved, and a surface illuminating device with high efficiency and good luminance uniformity can be obtained.

Further, when the flat light source of the present invention is used in, for example, a liquid crystal display device, it is possible to improve the lighting delay and the startability at a low temperature, and to obtain a backlight with high efficiency and good luminance uniformity.

[0020]

According to the flat light source of the present invention, the auxiliary electrode is provided close to one of the discharge electrodes, and the electrode on the light emitting region side is made substantially L-shaped, so that the distance between the externally derived portions is reduced. As a result, external power can be supplied without short-circuiting between the auxiliary electrode and the main discharge electrode. Further, by providing the auxiliary electrode in the vicinity of the substantially L-shaped corner, the movement of the electric charge in the substantially L-shaped corner having a small potential gradient can be increased, and the same luminance output as the peripheral part can be obtained. Can be.

[Brief description of the drawings]

FIG. 1 is a plan view of a flat light source according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a flat light source according to an embodiment of the present invention.

FIG. 3 is a waveform diagram showing a driving waveform of the discharge device.

FIG. 4 is a plan view of a flat light source according to another embodiment of the present invention.

FIG. 5 is a plan view of a flat light source according to another embodiment of the present invention.

FIG. 6 is a plan view of a flat light source according to another embodiment of the present invention.

FIG. 7 is a cross-sectional view of a flat light source showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Airtight container, 2 ... Front plate, 3 ... Back plate, 4, 5 ... Discharge electrode, 6 ... Auxiliary electrode, 7 ... Dielectric layer, 8 ... Phosphor, 9 ...
Discharge space, 10: discharge space of auxiliary electrode section, 11: protective film, 12, 13: drive voltage waveform, 14: insulating substrate, 15
... side plate, 16 ... light emission direction.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuji Arai 6-chome, Shinmachi 6-chome, Shinmachi, Ome-shi, Tokyo F-term in the Heater Lighting Division, Hitachi, Ltd. 2H091 FA41Z FA43Z GA02 GA11 LA05 LA18 5C039 EA02 5C043 AA04 AA18 BB04 CC16 CD08 DD36 DD37 DD39 EA09 EA16 5G435 AA02 BB12 BB15 EE09 EE26 EE29 EE33 GG25 HH06 HH12 HH16

Claims (8)

[Claims] An airtight container having a flat discharge space is formed by arranging a light-transmitting front plate and a rear plate substantially in parallel, and a phosphor is provided on the inner surface of the front plate and the inner surface of the back plate of the airtight container. Is applied, a pair of discharge main electrodes is provided over a predetermined length on mutually separated sides of the discharge space, an auxiliary electrode is provided in proximity to one frame side of the discharge main electrode, and the auxiliary electrode is provided. A flat light source characterized in that the adjacent discharge main electrodes are substantially L-shaped. 2. An airtight container having a flat discharge space by arranging a light-transmitting front plate and a rear plate substantially parallel to each other, and a phosphor is provided on the inner surface of the front plate and the inner surface of the rear plate of the airtight container. A pair of discharge main electrodes are provided over a predetermined length on mutually separated sides of the discharge space, and an auxiliary electrode is provided in proximity to one light emitting surface side of the discharge main electrode; Has a substantially L-shape. 3. The flat light source according to claim 1, wherein said auxiliary electrode is provided near a corner of said substantially L-shaped discharge main electrode. 4. The method according to claim 1, wherein the pair of discharge main electrodes and auxiliary electrodes are
The flat light source according to any one of claims 1 to 3, wherein the flat light source is provided on an inner surface of the front plate. 5. The flat plate type according to claim 1, wherein a dielectric layer is provided so as to cover a surface of the pair of discharge main electrodes and auxiliary electrodes provided on the front plate. light source. 6. The flat light source according to claim 1, wherein an auxiliary electrode is formed between a frame portion of said back plate and a front plate. 7. A liquid crystal display device using the flat light source according to claim 1 as a backlight. 8. An illuminating device comprising the flat light source according to claim 1. Description: