JPH09204880A - Electron gun and cathode ray tube using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the emission of unnecessary electrons from a part other than a cathode caused by the vapor deposition of barium and enhance the display quality of a cathode ray tube by using a field emitter array having the specified recessed shape in the cathode. SOLUTION: A field emitter array 10 in which plural field emission chips 14 are electrically connected with a lower electrode 11, and field is emitted with an electrode 13 arranged in the upper part of the chip 14 is used as a cathode of an electron gun. The upper outer circumferential part 13 of the field emitter array 10 comes in contact with a first electrode 1 to make the same potential as the first electrode 1, and the central part where the chips exist is formed in a recessed shape so as to become 50-200μm distal to the first electrode 1. Unnecessary electron emission from a part other than the cathode is eliminated, the design change of the part other than the cathode is unnecessary, and the display quality of a cathode ray tube can be enhanced without remarkably increasing cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube for converging an electron beam on a fluorescent screen to emit light, and deflecting and scanning the electron beam to display an image.

[0002]

2. Description of the Related Art A cathode ray tube emits an electron beam from a cathode and focuses the electron beam on a fluorescent screen by a main lens using an electric field or a magnetic field to obtain a light emitting point. Is a device that displays characters and images by deflecting and scanning the entire surface of the. The electron gun has a function of generating an electron beam and converging it on the phosphor screen. For this purpose, for example, Advanced in Electronics and Physics, Supplement 3, Narrow Angle Electron Guns and
Cathode ray tube (Advances in Electronics an
d ElectronPhysics ， suppl.3 ， Narrow Angle Electron
Guns and Cathode Ray Tubes, ACADEMIC PRESS 1968)
Is described in detail.

An oxide cathode is most widely used at present as a cathode which is a source of electrons. This is a nickel base containing a reducing agent coated with an oxide mainly composed of barium. Regarding this, dioxide coated cathode, Volume 1-2 (The Oxide-coated
Cathode, Vol.1-2, CHAPMAN & HALL, Ltd., 1951).

In recent years, impregnated cathodes have been used instead of oxide cathodes. This is an oxide mainly composed of barium contained in a porous material of tungsten.
Volume 128 Part 1 Number 1 Pages 19-32 (IEE P
roc., Vol. 128, Pt1, No. 1 (1981) 19-32). Both of these cathodes are hot cathodes using barium, and the oxide cathode is heated to about 750 ° C. and the impregnated cathode is heated to about 1000 ° C. before use.

By the way, barium may gradually evaporate by heating the cathode, adhere to the electrode of the electron gun, and emit electrons from the adhered portion. Since the electrons generated from this are different from the original trajectory of the electron beam for displaying an image, they are emitted at a position different from the original bright spot of the phosphor screen. This may deteriorate the display quality of the CRT.

This unnecessary electron emission is directly caused by the attachment of barium to the electron gun electrode, but barium enables electron emission of several amperes per square centimeter required for a cathode ray tube at a temperature of 1000 ° C. or less. It is an indispensable substance for hot cathodes. Other than hot cathodes using barium, there is a field emitter array (Field Emit Array) in which minute field emission tips are integrated at micron intervals.
ter Arrays). If this can be used, the barium deposition on the electrodes of the electron gun is eliminated, and the above-mentioned problem does not occur. For field emitter arrays, for example, Applications
Science 16: 277-291 1983 (Ap
Replications of Surface Science 16 (1983) 277-291), which enables electron emission of several amperes per square centimeter at room temperature.

Since CRTs are widely used in television broadcasting, computer terminals, and various display devices, their operating systems and internal configurations are almost uniform, and compatibility is emphasized, and they are designed to be manufactured at low cost. Therefore, even when the field emitter array is used in place of the oxide cathode or the impregnated cathode, it is desirable that the change in the design of other electron guns is unnecessary.

[0008]

An object of the present invention is to replace a conventional hot cathode with a field emitter in an electron gun for a cathode ray tube without changing the design of the electron gun other than the cathode and other parts. The challenge is to use arrays. As a result, a CRT with good display quality,
It is to provide it without causing a significant price increase.

[0009]

[Means for Solving the Problems] The above-mentioned problem is to provide an upper electrode, which is an extraction electrode of a field emitter array,
Assembled so as to be in contact with the first electrode counting from the cathode side. At this time, the surface of the upper electrode of the field emitter array has a concave shape, and the step difference between the concave upper portion and the concave bottom portion is 50 μ to 200 μ, and the concave bottom portion is formed. The range may be larger than the range of the opening of the first electrode.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the electron gun for cathode ray tubes of the present invention, which will be compared with the conventional example of FIG.

The conventional electron gun shown in FIG. 4 uses an oxide cathode 20 as a cathode, and the cathode is equipped with a heater 21 for heating. The electrodes of the electron gun have a first electrode 1 and a second electrode 2 in this order from the cathode side toward the phosphor screen, and the cathode 20, the first electrode 1 and the second electrode 2 are called a triode.
The triode extracts the electron beam 106 from the cathode and guides it to the main lens. The main lens focuses the electron beam on the phosphor screen, but when the electrostatic lens method is used, it is composed of several electrodes from the third electrode 3. Generally, the first electrode 1 is set to 0 V and the second electrode 2 is set to about 500 to 1000 V, and the current of the electron beam is adjusted by driving the cathode to 0 V to several tens of V.

The electron emission surface 24A of the cathode of the conventional electron gun is fixed to be separated from the cathode-side surface 1A of the first electrode 1 by 50 to 200 μm. The electron beam connects the intersections between the first electrode 1 and the second electrode 2 due to the above-mentioned potential relationship and positional relationship of the three poles, which is called a crossover 5. The main lens is designed to form an image on the fluorescent screen by using the crossover 5 as a virtual light source. In order for the electron trajectories to form the crossover 5, it is necessary for the electron emission surface 24A of the cathode and the first electrode 1 to maintain a constant distance as described above.

In the electron gun of the present invention shown in FIG. 1, a field emitter array 10 is used for the cathode. The structure of the field emitter array 10 is shown in FIG. 2, which causes field emission between the lower electrode 11 electrically connecting the plurality of field emission tips 14, the insulating layer 12, and the field emission tips 14. It is composed of an upper electrode 13 for effecting. Generally, the upper electrode 13 is a flat surface having fine holes in the electric field tip portion, but in the electron gun of the present invention, the upper electrode 13 has a concave shape, and the central portion 13B (concave portion) having the field emission tip is formed. The bottom of the shape is located far from the first electrode. The upper electrode is in contact with the first electrode 1 at the outer peripheral portion 13A (upper concave portion), and the upper electrode 13 has the same potential as the first electrode 1.

The structure of the cathode ray tube electron gun other than the cathode portion 10 is exactly the same as the conventional one, and the electrode potential is also the same. However, in the present invention, the drive of the cathode is performed by the voltage of the lower electrode 11. In this case, a voltage of 0V to minus tens of volts is applied to the lower electrode. By making the voltage of the lower electrode negative, electrons are emitted from the field emission tip 14 and the central portion 13B of the upper electrode, which serves as a virtual cathode surface of the electron, is emitted.
Is separated from the cathode-side surface 1A of the first electrode 1, and the electron trajectory can form a crossover as in the conventional electron gun.

By thus forming the upper electrode 13 of the field emitter array 10 in a concave shape, the structure and voltage of the cathode ray tube electron gun other than the cathode portion can be used as they are. Here, the central part 1 of the upper electrode
The distance between 3B (concave bottom) and the cathode-side surface 1A of the first electrode is such that the crossover 5 is connected between the first electrode 1 and the second electrode 2 so that the oxide cathode 20 in the conventional electron gun is And the distance between the first electrode 1 and the first electrode 1. The distance is 50 μ to 200 μ. Also, the central portion 13B
The range of the (concave bottom portion) should be as wide as possible so as to be the same as the electric field distribution of the conventional electron gun, but it may be substantially the same as or wider than the opening 1B of the first electrode 1.

FIG. 3 shows a cathode ray tube 100 using the electron gun of the above embodiment. The electrons 106 emitted from the field emitter array 10 are focused on the fluorescent screen 104 by the electrode 102 of the electron gun. At this time, the electron beam 106 is scanned by the deflection coil 103 over the entire phosphor screen. The field emitter array 10, the electron gun electrode 102, and the fluorescent screen 104 are held in a glass container 105 in a vacuum. The cathode ray tube 100 using the field emitter array 10 has no unnecessary electron emission from other than the original cathode, and does not cause deterioration of display quality. Further, in the case of the electron gun of the above-described embodiment, there is no design change except for the cathode portion, the same production efficiency as in the past can be expected, and the price is not significantly increased.

[0017]

According to the present invention, a field emitter array can be used as a cathode without a significant change in design, and unnecessary electron emission from an electron gun electrode is prevented, and a CRT having a good display quality can be manufactured at a low price. It can be produced without causing a significant rise.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of an electron gun according to an embodiment of the present invention.

FIG. 2 is a partial sectional perspective view of a field emitter array portion used in the electron gun of the present invention.

FIG. 3 is a cross-sectional view of a cathode ray tube according to an embodiment of the present invention.

FIG. 4 is a sectional view of a conventional example of an electron gun.

[Explanation of symbols]

1, 2, 3 ... First, second, third electrodes, 5 ... Crossover, 10 ... Field emitter array, 11 ... Lower electrode, 12 ... Insulating layer, 13 ... Recessed upper electrode, 14 ...
Field emission tip, 106 ... Electron beam.

Front page continuation (72) Inventor Matsu ▲ Saki ▼ Naoko 3300 Hayano, Mobara-shi, Chiba Electronic device division, Hitachi, Ltd. (72) Emiko Yamada 3300 Hayano, Mobara, Chiba Hitachi, Ltd. Electronic device business Department

Claims (3)

[Claims] 1. A triode part for generating an electron beam and a main lens part for converging the electron beam. The triode part is composed of a cathode and two electrodes. In an electron gun for a cathode ray tube, which has an opening through which an electron beam from the cathode passes, the first electrode counting from the cathode side has a lower potential than the second electrode, the cathode is a plurality of fine ones. Field emission tips are arranged on a plane, and a lower electrode for electrically connecting the plurality of field emission tips and a plurality of the field emission tips simultaneously generate an electric field to cause field electron emission. A field emitter array comprising an upper electrode of, and an insulating layer electrically isolating the lower electrode and the upper electrode, wherein the electrode surface of the upper electrode of the field emitter array is The electrode surface including the electron emission region in which the field emission tip is present is recessed so as to be far from the first electrode as compared with the electrode surface of the non-electron emission region located in the outer peripheral portion of the electron emission region. An electron gun having a shape and being configured such that at least a part of the non-electron emission region of the upper electrode is in contact with the first electrode. 2. The concave bottom portion, which is an electrode surface including the electron emission region, of the upper electrode of the concave field emitter array, and the electrode surface of the non-electron emission region according to claim 1. The difference in height position of the concave upper surface is 5
An electron gun having a range of 0 μ to 200 μ, and a size of a range of the concave bottom portion is larger than a range of the opening portion of the first electrode. 3. A cathode ray tube using the electron gun according to claim 1.