JPH03261038A - Plasma display device - Google Patents

Abstract

PURPOSE:To prevent occurrence of brightness dispersion for a picture image while reducing the starting voltage and maintenance voltage of a discharge by forming a primer metal layer of a cathode out of silver or silver alloy, and laminating a layer of LaB6 on its surface. CONSTITUTION:A horizontal stripe of a cathode 6 makes light emission of a high brightness in dots at intersectional points with stripes of anodes 5 on the closer side to a circuit connecting terminal, while light emission of a low brightness in dots is performed at an end part on the opposite side. In the meanwhile, the adjacent cathode 6 has a circuit connecting terminal in the opposite right/left position, so light emission in dots at intersections with the anode 5 has an opposite brightness distribution, and a difference generated for each line between the right and the left of a picture generates a brightness dispersion. A primer metal layer 7 for the cathode 6 is of silver or silver alloy, and a layer 8 of LaB6 is laminated. Silver or silver alloy has almost no change in its resistance value if it is baked in O2, and it shows a low resistance value by thick film printing. By this constitution, light emission in dots of almost uniform brightness distribution for the whole length of the stripes of the metal cathodes 6 can be achieved, and occurrence of brightness dispersion can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method of forming a plurality of glass plates on the inner surface of one of a pair of flat glass plates facing each other to form the front and rear walls of a flat envelope. A transparent striped anode is attached, a large number of striped cathodes intersecting the anode are attached on the inner surface of the other glass flat plate, and a discharge gas is hermetically sealed in the envelope to form a dot matrix. The present invention relates to a plasma display device.

2. Description of the Related Art In general, the cathode of a plasma display device as described above is made of nickel powder. That is, it is obtained by printing a thick film using a baset prepared by kneading nickel powder with a binder as an ink, and then firing the coated film. In addition, after forming a base metal layer made of nickel by the above-mentioned thick film printing method, LaB
A LaBe cathode with six layers is also known. Such La
In a plasma display device using a B6 cathode, the discharge starting voltage and discharge sustaining voltage can be set low, so that not only can a relatively inexpensive driving IC with low withstand voltage be used, but also power consumption can be reduced.

The cathode of a plasma display device disclosed in JP-A-6.0-221926 is obtained by thick-film printing a paste containing LaB6 powder on a nickel base metal layer formed by a thick-film printing method. After the coating film is fired, cathode forming is performed using high current gas discharge. In addition, cathodes that have a LaBB layer formed by methods such as thin film deposition or plasma spraying are also known, but in any case, since LaBB has a low work function, such LaBB
A plasma display device equipped with 6 cathodes has a display discharge voltage of 3 times lower than that of a conventional plasma display device using nickel cathodes.
It can be lowered by 0V to 50V. Also, LaB6
Since it has a high melting point, it also has the advantage of being highly resistant to spatter.

Although LaB6 is a compound, it is a unique material that has conductivity comparable to metal. If this is to be introduced by thick film printing, which is convenient for forming the cathode of a plasma display device, it must be handled as a powder as described above. However, powdered LaB6 has low conductivity due to the contact resistance of its surface, and if the entire striped cathode is formed only from LaB6 powder, it will be difficult to pass the current necessary for display discharge throughout the cathode. . Therefore, as described above, the LaBe layer is printed as a thick layer on the base metal layer made of nickel.

Problems to be Solved by the Invention However, even with a striped LaB6 cathode having a thick-film printed nickel underlayer, discharge and light emission occur between one end on the side near the circuit connection terminal and the other end on the opposite side. This causes a difference in brightness. To explain this with reference to Fig. 2, the horizontally long striped cathode 1 emits high-intensity dot-shaped light at the side near the circuit connection terminal, that is, at the three-dimensional intersection with the striped anode A1. The dot-shaped light emission at the intersection with 040 to the anode on the opposite side has low brightness. Further, the dot-shaped light emission at the three-dimensional intersection with the anode A320 located in the middle has intermediate brightness. on the other hand,
Since the cathode 2 located next to the cathode 1 has a circuit connection terminal on the left and right opposite to the circuit connection terminal 1 on the cathode, the dot-shaped light emission at the three-dimensional intersection with the anode A1 is low. The dot-shaped light emission at the three-dimensional intersection with the anode A640 has high brightness.

If the brightness of the dot-like light emission generated on the surface of the striped cathode differs from line to line on the left and right sides of the screen, uneven brightness will occur in the relevant screen area, making it difficult to display high-definition images. It disappears.

Also, since the discharge current tends to concentrate in high brightness areas,
This results in further reduction in brightness in adjacent low brightness areas, making it more likely to cause malfunctions.

Means for Solving the Problems The present invention has been made to solve the above-mentioned conventional inconveniences. According to the present invention, the base metal layer of the cathode is formed of silver or a silver alloy, and on the surface thereof, Six LaB layers are stacked one on top of the other.

The specific resistance of working silver (20°C) is 1.62X10-6 Ω-cm
and the specific resistance of nickel (7,24X10-6Ω-C10
), the difference in resistance value is not only smaller than that of silver paste, but also widens even further when thick film is printed as silver paste. In other words, the sheet resistance of nickel is approximately 50 IIlΩ/mouth, whereas
The sheet resistance of silver is one-tenth of that, about 5 mΩ/hole. Moreover, silver alloys such as silver and silver-palladium alloys have almost no change in resistance even when subjected to firing treatment in an oxygen atmosphere, so dot-shaped light emission with an almost uniform brightness distribution over the entire length of the striped cathode. can be generated, and the occurrence of brightness unevenness as described above can be prevented.

Embodiment As shown in FIG. 1, a pair of flat glass plates 2 and 3, which are arranged opposite to each other to form the front and rear walls of a flat envelope 1, have a frit glass layer 4 in the shape of a rectangular frame. It is hermetically sealed through the A large number of striped anodes 5 attached to the inner surface of one glass flat plate 2 are made of a transparent conductive film made of IT○, and a large number of striped cathodes 6 attached to the inner surface of the other glass flat plate 3 are made of a transparent conductive film made of IT○. , each line has circuit connection terminals at different left and right ends, and has a base metal layer 7 made of silver and La provided on the surface thereof.
It consists of 86 layers and 8. The envelope 1 is filled with a discharge gas consisting of neon and argon (0.5% argon).

Although only three cathodes 6 are shown in the figure, there can be as many as 480 cathodes 6 and 640 anodes 5 for high-definition image display.

The base metal layer 7 of the cathode 6 is made of powdered silver together with a binder.
This is a thick film printed using kneaded silver paste as ink, and the layer thickness is approximately 10 μm. The La86 layer 8 is also thickly printed to a layer thickness of about 10 μm, and is integrated with the base layer 7 by firing treatment.

When all dots of such a plasma display device were lit with an average current of 160 mA, even after 1.600 hours had elapsed, the discharge sustaining voltage difference between two adjacent cathodes at both ends could be suppressed to 1 V or less, respectively. No unevenness in brightness was observed at all.

Note that when a plasma display device incorporating a conventional LaB6 cathode with nickel as the base metal layer is lit on all dots under the same operating conditions as described above, the discharge sustaining voltage difference after 200 hours has elapsed is several V or more. This results in considerable brightness unevenness between the left and right sides of the screen. In the above example, silver was used for the underlying metal layer, but the specific resistance (at 20°C) was 2X10-
A silver alloy such as a silver-palladium alloy may be used as long as it is less than GΩ-CIl+.

Effects of the Invention As described above, according to the present invention, by using a LaBe cathode, it is possible to reduce the discharge starting voltage and the discharge sustaining voltage, and to generate dot-shaped light emission with a uniform luminance distribution over the entire length of the cathode. It is possible to prevent uneven brightness from occurring.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a plasma display device embodying the present invention, and FIG. 2 is a schematic plan view showing the arrangement relationship between a cathode and an anode of a conventional plasma display device. 1... Envelope, 2, 3... Glass flat plate, 5... Anode, 6... Cathode, 7...
... Base metal layer, 5LaB6 layer.

Claims (1)

[Claims] A large number of transparent striped anodes are attached to one inner surface of a pair of flat glass plates facing each other to form a front wall and a back wall of a flat envelope, and a large number of transparent stripe-shaped anodes intersect with the anodes. In a plasma display device in which a striped cathode is attached on the inner surface of the other flat glass plate, and a discharge gas is hermetically sealed in the envelope, the cathode has circuit connection terminals at different left and right ends for each line. and a base metal layer formed by thick film printing and a LaB_6 layer overlaid on the surface of the base metal layer, the base metal layer being made of silver or a silver alloy. Display device.