JPH0355736A - Linear hot cathode - Google Patents

Abstract

PURPOSE:To enhance extension of life such as long-time maintenance of high brightness characteristic of display device by adhering and forming a nickel thin film containing silicon and magnesium on a linear tungsten metal, and adhering thereon an electron radiating material in which scandium oxide is mixed to an alkali earth metal oxide containing barium. CONSTITUTION:As a cathode wire, tungsten is used, and a nickel thin film is adhered to this tungsten wire 3. The nickel thin film is evaporated by vacuum evaporation method. Either or both of silicon and magnesium showing reduction effect are contained in the nickel. As a cathode, an electrodepositing solution by an electron radiating material consisting of an alkali earth metal compound such as barium, strontium, and calcium containing at least barium oxide and in which scandium oxide is contained is used. This solution is held on the cathode wire 3b in a determined thickness by electrodepositing method to form the cathode 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a linear hot cathode used in vacuum tubes, CRTs, fluorescent display tubes, etc. [Prior art] Various devices using linear hot cathodes have been proposed in the past.
For example, there is a flat panel display device as disclosed in Japanese Patent Application Laid-Open No. 60-184744. FIG. 2 is a schematic cross-sectional view showing such a conventional flat panel display device. , cathode wires 3 holding electron-emitting substances and forming cathodes 4 are provided at predetermined intervals. A control electrode 5 is disposed on the insulating substrate 1 in correspondence with each cathode 4, and a grid electrode 6 provided with a through hole 6a at a position corresponding to each cathode 4 above the cathode wire 3; Above this grid electrode 6, anodes 8 coated with phosphor 7 are arranged at positions corresponding to the respective cathodes 4 at required intervals in the upward and downward directions, respectively.

The cathode wire 3 is made of tungsten, and the cathode 4 is made of ternary carbonate of barium, strontium, and calcium ((Ba.Sr,Ca)Cow) by electrodeposition or coating on the surface of the cathode wire 3. is deposited and thermally decomposed in the process of evacuating the inside of the display device container, converting the carbonate into oxides ((Ba, Sr, Ca)
0). At this time, the tungsten of the cathode wire 3 reduces BaO in the electron emitting material through the following reaction to form excess 8a. This 8a
moves to the cathode surface during diffusion, forms donors in BaO, and contributes to the process.

6 BaO + W −+ BaJO,, + 3 8
a Next, the operation will be explained. When the cathode wire 3 is heated to about 700'C by supplying power to both ends thereof, electrons are emitted from the surface of the cathode 4. At this time, if a positive electrode is applied to the glissode electrode 6 and the anode 8, the electron beam is guided to the phosphor 7 through the through hole 6a and excites the phosphor 7. On the other hand, if a negative voltage is applied to the TFi electrode 5, the electric field around the cathode 4 becomes negative with respect to the cathode 4b, and electron emission from the cathode 4 can be stopped. Therefore, for example, a positive pulse voltage is applied to the control electrode 5. By doing so, the emission of the electron beam can be controlled.

By the way, such a linear hot cathode is used in the process of replacing the carbonate with an oxide or during the initial operation of a display device. Due to the influence of impure gas emitted from the locking part 2, etc., the initial voltage current decreases, causing problems such as lowering the brightness of the display device and requiring a long time for the display device manufacturing exhaust process. there were. Previously, the inventors proposed a mixture containing 0.2 to 20% by weight of a rare earth metal oxide and an alkaline earth metal oxide containing barium oxide as a solution to the above problems. He proposed a linear hot cathode in which an electron-emitting material with a weight ratio of barium oxide to rare earth metal oxide of 0.4 to 60 was held on the surface of a linear heat-resistant metal, and achieved great results (Tokugan Sho No. 62-122053).

[Problem to be solved by the invention]

As we continued to research and develop such linear hot cathodes, we discovered that BasWO, which is produced by the above reaction formula,
* may accumulate over time at the interface between the heat-resistant metal and the electron-emitting material, separating the two, and as a result may impede the survival of excess Ba. On the other hand, it was confirmed that the suppression of the growth rate also reduces the generation of Ti-Ba in the above reaction formula, which is one of the causes of deterioration of the life characteristics. In view of this problem, the inventors have made extensive studies and have arrived at this invention.

[Means for Solving the Problems] The linear hot cathode of the present invention has a Nifkel thin film containing silicon and magnesium as a reducing agent deposited on a linear tungsten metal, and an alkali film containing at least barium on the Nifkel thin film containing silicon and magnesium as a reducing agent. It is characterized by being coated with an electron-emitting material that is a mixture of earth metal oxide and scandium oxide.

[Function] In this invention, the Ninokel thin film is deposited on the tungsten metal layer of the base to avoid direct contact with the electron emitting material layer, so that the above Bal at the interface between the two is avoided.
Middle class lifestyles such as WOi will be suppressed. And the above B
A = WO, Ba life reaction at the time of life reaction! It is presumed that the reduction in the amount of ITS is compensated for by the reducing action of reducing silicon or magnesium in the nickel thin film, and that the above-mentioned deterioration in life characteristics is eventually avoided.

〔Example〕

The present invention will be specifically explained below with reference to Examples.

FIG. 1 is a schematic cross-sectional view showing the main parts of a display device using a linear hot cathode according to an embodiment of the present invention, in which 1 is an insulating substrate made of a glass plate, a ceramic plate, etc. 2 is a locking portion mainly formed as a metal protrusion or rib, and 3 is a silicone locking portion. Nickel (containing magnesium)
1!9 is coated with a tungsten cathode wire. 4 is a cathode formed on the cathode wire 3 at required intervals in its longitudinal direction, 5 is a control electrode, 6 is a glisode electrode, and 8 is an anode. Reversible locking portions 2 are provided at regular intervals on the insulating substrate 1, and the cathode wire 3 is passed to each of the locking portions 2, and the cathode 4 formed thereon is adjacent to the locking portions 2. .It is stretched so that it is located between the two. Each cathode 4 is disposed on the insulating substrate 1.
A control electrode 5 is provided at a position facing the cathode 4, and a through hole 6 is provided above the cathode wire 3 at a position facing the cathode 4.
A grid electrode 6 with an opening a is disposed above the grid electrode 6, and an anode 8 having a phosphor 7 attached thereto at a position facing the cathode 4 is disposed at intervals in the vertical direction.

The structure described above is substantially the same as the conventional product shown in FIG. 2, except that the cathode wire 3 is coated with the Nisokel thin film 9.

Tungsten is used as the cathode wire, and a Ninkel thin film is coated on this tungsten wire. The nickel thin film is deposited by a general vapor deposition method. Ninkel contains 0.05 to 5% by weight of silicon or magnesium, or both, which have a reducing effect.

The content of silicon or magnesium in Nisokel is not strictly limited, but if it is below the lower limit, its effect will be poor, and if it exceeds the upper limit, it will be difficult to form a Nisokel film, both of which are undesirable. Next, as the cathode, an electrodeposition liquid made of an alkaline earth metal compound such as barium, strontium, or calcium containing at least barium oxide, and an electron emitting substance containing scandium oxide is used. Specifically, Bad:
6 4, SrO: 3 2, CaO: 4 each weight%
0.2 to 2 scandium oxide based on the total amount of
It contained 0% by weight. Each cathode was formed by holding this on the cathode wire 3 to a film thickness of 8 μm using a conventional electrodeposition method.

Next, this is heated in the exhaust process of the display device, and carbonate (Ba, Sr, Ca) COs Scz (COs)*
(8aSr, Ca) O-SCzOt to produce display devices having cathodes with different composition ratios.

By interposing the nickel thin film containing silicon or magnesium between the tungsten wire and the electron emitting material layer of the cathode, for example, the following formula BaO + St-4Ba + SiOBaO + M
g-4Ha + BaO in electron emitting materials such as MgO
is reduced and Ba is liberated, making it possible to supply a sufficient amount of Ba.

Since there is no direct contact between the tungsten wire and the electron emitting material, the above-mentioned intermediate layer 11aJO. This eliminates the problem caused by the generation of . Actually, in the above-mentioned display device, a nickel metal layer containing 0.1% by weight of silicon (or magnesium) was deposited on the tungsten wire to a thickness of 10 μm by vapor deposition. And on top of this, Ba + Sr, C of the above group precepts
a) The display of the electron emitting material made of carbonate mixed with 5 wt% scandium oxide (example product) and the product without the nickel metal layer (comparative example product) The high brightness characteristic maintenance time of the device was measured.As a result, the time for maintaining the high brightness characteristic of the device was approximately 10,000 hours for the example product of the present invention, while it was 7,000 hours for the comparative example product.

In other words, the life characteristics of this invention are improved by about 4 times compared to conventional products.
It reached a certain percentage. [Effects of the Invention] As explained above, the cathode of the present invention has excellent effects in increasing the brightness of display devices and maintaining the high performance of electron tube devices and the like over a long period of time, thereby extending the life of the cathode.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a display device using the product of the present invention, and FIG. 2 is a schematic sectional view showing a conventional display device. DESCRIPTION OF SYMBOLS 1... Insulating base temporary, 2... Locking part, 3... Cathode tungsten wire 4... Cathode, 5... Control ii
8i, 6... Grid electrode, 7... Fluorescent substance, 8...
・Anode, 9...Silicon. Magnesium-containing nickel fjlllW. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] Silicon as a reducing agent on the linear tungsten metal,
A linear hot cathode characterized in that a nickel thin film containing magnesium is deposited, and an electron emitting material made of an alkaline earth metal oxide containing at least barium mixed with scandium oxide is deposited thereon.