JPH04280048A - Flat type image display device - Google Patents

Abstract

PURPOSE:To provide a clear image and a high-intensity image by constituting an electron source with the primary electron source generating primary electrons and the secondary electron source amplifying the primary electrons from it via the Malter effect. CONSTITUTION:When voltage is applied across a cathode 16 and extracting electrodes 19a, 19b, primary electrons are extracted from the cathode 16 into an opening section 17, and the electrons are accelerated by an upper accelerating grid 22b and a lower accelerating grid 22a. The primary electrons are slantly radiated on the surface of a Cs oxide 15, and secondary electrons are emitted outward from the Cs oxide 15. The Cs oxide 15 is electrified to plus, the electric field is applied to an Al oxide film 14 functioning as a dielectric substance, and the strong electric field is generated near the very thin Al oxide film 14. A large quantity of electrons are extracted from an Al film 13 by the strong electric field via the Malter effect, the electrons are accelerated by the electric field between it and an anode 24, and a large quantity of electrons reaching the anode 24 illuminate a phosphor layer 25.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat image display device, and more particularly to a flat image display device in which a light emitter emits light by electron beams from a plurality of electron sources.

0002

[Prior Art] CRTs in currently mainstream television receivers
Planar image display devices are being considered as alternative image display devices, and examples of such planar image display devices include liquid crystal displays (LCDs), electroluminescent devices (ELDs), and plasma display devices ( In addition, field emission type image display devices are also attracting attention in terms of screen brightness. Here, to briefly explain the field emission type image display device, a conical cathode made of molybdenum or the like with a diameter of 1.0 microns or less formed on a substrate using a semiconductor manufacturing process is used as an emission source. A plate-shaped gate electrode is formed on the tip side of the cathode, and has a hole corresponding to each cathode. The gate electrode is separated from the tip of the cathode, and a high voltage is selectively applied between the two to generate field emission.
An electron beam is extracted from the cathode. and,
A desired screen is displayed by irradiating this electron beam onto a light emitting body (phosphor) arranged on the back surface of the anode. Regarding such a field emission type image display device, for example, U.S. Pat.
There is a description of this in Publication No. 336, etc.

FIG. 4 is a cross-sectional view of an example of a conventional field emission type image display device. A plurality of pointed cathodes 102 are arranged and formed on a base 101 . A gate electrode 104 is formed on the base 101 with an insulating film 103 interposed therebetween. Electrons are extracted by the voltage applied between the gate electrode 104 and the cathode 102. This gate electrode 104 has a hole 104a on the cathode 102, and the gate electrode 104 has a hole 104a on the cathode 102.
The electron beam from 2 passes through the hole 104a. and,
A planar anode 105 facing the base 101 to which a high voltage is applied is irradiated with the electron beam, and the electrons reach the light-emitting layer 106 on the back surface of the anode 105, causing the light-emitting layer 106 to emit light.

0004

[Problems to be Solved by the Invention] However, in such a field emission type image display device, the point-shaped cathode 1
The electron beam emitted from the electron beam 02 is easily scattered, and the emission intensity in the light emitter layer 106 is not sufficient. Therefore, new technical ingenuity was needed to form a brighter screen.

SUMMARY OF THE INVENTION In view of the above technical problems, the present invention aims to provide a flat image display device that uses an electron source that emits a powerful electron beam to improve the luminous intensity of a light emitter. do.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the flat image display device of the present invention includes a base, a plurality of electron sources disposed on the base, and a vacuum space for the electron sources. The electron source includes a primary electron source that generates primary electrons, and a light emitting body provided on the opposite side of the electrode to the base body, and the electron source includes a primary electron source that generates primary electrons, and a primary electron source that generates primary electrons. It is characterized by comprising a secondary electron source that amplifies secondary electrons by the Malta effect. Secondary electron sources that generate electrons due to the Malta effect include laminated films of a cesium oxide film, an aluminum oxide film, and an aluminum film, a laminated film of a magnesium oxide film, a nickel oxide film, and a nickel film, etc. used. A gate electrode may be provided between the electron source and the electrode to control the electron beam emitted toward the electrode.

[0007]

[Operation] Only a small amount of electron beam can be generated by field emission alone, but by using this as a primary electron source and amplifying the primary electrons from the primary electron source by the Malta effect, a large amount of electron beams can be generated. Can generate a beam. The Malta effect is a phenomenon in which a large amount of electrons are extracted from a metal when a strong electric field is applied to an insulating thin film at the interface. Since the secondary electron source generates a large amount of electrons, the emission intensity of the light emitter can be improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment] This embodiment is a flat image display device using the Malta effect as a secondary electron source, and the main part thereof is shown in FIG. A secondary electron source 12 is formed in a part of a base 11 made of an insulator.

This secondary electron source 12 has an aluminum film 13 and a thin aluminum oxide film 1 laminated on the aluminum film 13 in a groove 23 formed in a base 11.
4 and a cesium oxide film 15 laminated on the aluminum oxide film 14. A ground potential is applied to the lowermost aluminum film 13. Further, the aluminum oxide film 14 formed between the aluminum film 13 and the cesium oxide film 15 is a thin film of about 500 to 1000 angstroms. This secondary electron source generates a large amount of electron beams by a mechanism described later.

A primary electron source 20 is formed on the base 11 in the vicinity of the secondary electron source 12, which has a laminated structure of three metals and metal oxide films. This primary electron source 20 is
It has a cathode 16 having a sawtooth field emission surface as an emission source. FIG. 2 is a perspective view showing the shape of the cathode 16. The cathode 16 is formed on the lower insulating film 18a and is made of a flat metal material such as molybdenum or tungsten. Field emission surface 33 of this cathode 16
The sides have a sawtooth shape in which peaks 31 and valleys 32 are arranged alternately, and an electric field is concentrated on the protruding peaks 31 to extract primary electrons. This cathode 16 is a lower insulating film 18a.
and an upper insulating film 18b, and an opening 17 is formed on the field emission surface 33 side.

[0012] Inside this opening 17, an upper extraction electrode 19b, a lower extraction electrode 19a, an upper acceleration grid 22b, and a lower acceleration grid 22a face. The upper extraction electrode 19b is arranged at the end of the secondary electron source side of one of the upper insulating films 18b sandwiching the cathode 16 therebetween, and the lower extraction electrode 19a is arranged at the end of the other lower insulating film 1 sandwiching the cathode 16 therebetween.
It is arranged at the end of the secondary electron source side of 8a. These upper lead-out electrodes 19b and lower lead-out electrodes 19a are connected to the cathode 1.
Primary electrons are extracted from the cathode 16 by applying a required voltage to the upper extraction electrode 19b and the lower extraction electrode 19a. A lower acceleration grid 22b is arranged on the main surface of the base body with a lower interlayer insulating film 21a interposed between it and the lower extraction electrode 19a. Further, the upper lead-out electrode 1
9b, an upper acceleration grid 22a is formed with an upper interlayer insulating film 21b interposed therebetween. The upper acceleration grid 22b and the lower acceleration grid 22a are made thicker than the extraction electrodes 19b and 19a, and a voltage higher than that of the extraction electrodes 19b and 19a is applied to the primary electrons in the opening 17. To accelerate. At this time, the energy given to the primary electrons is, for example, about 50 to 100 eV.

These primary electron sources 20 and secondary electron sources 12
An anode 24 is disposed as an electrode facing the base 11 formed adjacent to the substrate 11 . A vacuum space is provided between the base body 11 and the anode 24, and the main surface of the base body 11 and the planar anode 24
are arranged approximately parallel to each other. A high voltage is applied to this anode 24, and a large amount of electrons generated by the secondary electron source 12 reach the anode 24. A light emitter layer 2 is provided on the back surface of the anode 24 on the vacuum space side.
5 is provided, and electrons collide with this luminous body layer 25, causing the luminous body to emit light. The light emitter layer 25 exists sandwiched between the anode 24 and the front panel glass 26. Front panel glass 2
6 is made of transparent glass, and images are displayed through this front panel glass.

The flat image display device of this embodiment having such a structure has a cathode 16 and extraction electrodes 19a, 19b.
By applying a voltage between the cathode 16 and the opening 1
Primary electrons are extracted within the grid 7, and the primary electrons are accelerated by the upper acceleration grid 22b and the lower acceleration grid 22a. The accelerated primary electrons are obliquely irradiated onto the surface of the cesium oxide 15, causing the cesium oxide 15 to emit secondary electrons to the outside. As a result of the secondary electrons being emitted in this way, the cesium oxide 15 becomes positively charged. Then, an electric field is applied to the aluminum oxide film 14 that functions as a dielectric, and the aluminum oxide film 1
Since 4 is an extremely thin film, a strong electric field is generated near the aluminum oxide film 14. A large amount of electrons are extracted from the aluminum film 13 by this strong electric field (Maltese effect) and are accelerated according to the electric field between the aluminum film 13 and the anode 24 . The large amount of electrons that have reached the anode 24 reach the luminescent layer 25, causing the luminescent layer 25 to emit light at that portion. At this time, since the amount of electrons is large, the emission intensity is strong.

As described above, in the flat image display device of this embodiment, a large amount of electrons are transferred to the light emitting layer 2 by utilizing the Maltese effect.
Collision with 5. Therefore, the light emission intensity for image display can be significantly improved.

In the image display device of this embodiment, a laminated film of the cesium oxide film 15, the aluminum oxide film 14, and the aluminum film 13 is used as the secondary electron source, but the present invention is not limited to this. It is also possible to use a laminated film of a magnesium oxide film, a nickel oxide film, and a nickel film.

[Second Embodiment] The flat image display device of this embodiment has a structure having a gate electrode, as shown in FIG.

The image display device of this embodiment differs from the image display device of the first embodiment in that a gate electrode 41 is formed, and other parts are the same as the first embodiment. Therefore, the same reference numerals are used in FIG. 3 to illustrate the figures, and redundant explanation will be omitted.

The gate electrode 41 is formed on an interlayer insulating film 42 formed on the substrate 11 and the upper acceleration grid 22a. The interlayer insulating film 42 and the gate electrode 41 are opened above the secondary electron source 12, and the 2 electrons passing through the opening 46
A large amount of electrons from the secondary electron source 12 is controlled. The potential of gate electrode 41 is controlled by switch 43. The switch 43 switches the potential of the gate electrode 41 to the ground terminal 45 or the required voltage terminal 44, and when the potential of the gate electrode 41 reaches the ground level, electrons from the secondary electron source 12 are cut off and the gate electrode 41 When the potential of the secondary electron source 12 reaches the required positive voltage, electrons from the secondary electron source 12 pass through the gate electrode 41 and collide with the light emitting layer 25.

By adding such a gate electrode 41, a large amount of electrons from the secondary electron source 12 can be controlled using the Maltese effect. Further, as in the first embodiment, the light emission intensity for image display can be significantly improved, and clear images and images with high brightness can be provided.

[0021] Also in this second embodiment, the laminated film that generates the Malta effect is not limited to a laminated film consisting of a cesium oxide film, an aluminum oxide film, and an aluminum film, but a magnesium oxide film, a nickel oxide film, etc. It can be a laminated film of a nickel film or the like.

[0022]

Effects of the Invention As described above, the flat image display device of the present invention uses the Maltese effect to amplify the primary electrons from the primary electron source and transfer a large amount of electrons from the secondary electron source to the opposing electrodes ( It is possible to irradiate the light emitter on the anode) side. Therefore, the light emission intensity for image display can be significantly improved, and clear images and images with high brightness can be provided. Furthermore, by adding a gate electrode, a large amount of electrons from the secondary electron source can be reliably controlled, contributing to the provision of clear images and images with high brightness while increasing the emission intensity of the light emitter.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an example of a flat image display device of the present invention.

[Fig. 2] A cross-sectional perspective view showing the shape of the cathode portion of the above example.

FIG. 3 is a schematic cross-sectional view of another example of the flat image display device of the present invention.

[Fig. 4] A schematic cross-sectional view of an example of a conventional field emission type image display device.

[Explanation of symbols]

11...Substrate 12...Secondary electron source 13...Aluminum film 14...Aluminum oxide film 15...Cesium oxide film 16...Cathode 17...Openings 18a, 18b...Lower, upper insulating film 19a, 19b...Lower, upper extraction electrode 20...Primary electron sources 21a, 21b...Lower and upper interlayer insulating films 22a, 22b
...Lower and upper acceleration grids 24...Anode 25...Light emitter layer 26...Front panel glass 41...Gate electrode

Claims (4)

[Claims] Claim 1: A base body, a plurality of electron sources disposed on the base body, an electrode facing the electron source through a vacuum space, and a light emitting body provided on the opposite side of the electrode from the base body. A planar electron source comprising a primary electron source that generates primary electrons and a secondary electron source that amplifies the primary electrons from the primary electron source by the Malta effect. Image display device. 2. The flat image display device according to claim 1, wherein the secondary electron source comprises a laminated film of a cesium oxide film, an aluminum oxide film, and an aluminum film. 3. The flat image display device according to claim 1, wherein the secondary electron source comprises a laminated film of a magnesium oxide film, a nickel oxide film, and a nickel film. 4. The flat image display device according to claim 1, further comprising a gate electrode provided between the electron source and the electrode for controlling the electron beam emitted toward the electrode.