JPH07161283A - Field emission type cathode - Google Patents

Abstract

PURPOSE:To provide a good focus characteristic without generating the decrease of brightness. CONSTITUTION:In a field emission type cathode 19, many pattern-shaped fine cold cathodes 3 are arranged on a conductive base unit 2, and an electron emitting emitter area 20 is formed on this base unit 2. The emitter area 20 is constituted such that electron emitting density is almost uniformly formed over a total region of the emitter area 20, to obtain current density of an electron beam almost uniform from the center part of the emitter area 20 over to the periphery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission type cathode, and more particularly to a field emission type cathode which has a uniform flat electron emission density to obtain good focus characteristics.

[0002]

2. Description of the Related Art A field emission type cathode of this type is one in which a large number of minute cold cathodes are arranged in a pattern on a conductive substrate and an emitter area for electron emission is formed on the substrate. Compared to hot cathodes, the degree of integration can be increased to increase the cathode current density, the large current can be controlled by a low drive voltage, it can be manufactured using semiconductor manufacturing technology, and it is suitable for high precision and mass production. It has features that it can be activated and the spread of velocity distribution of emitted electrons is small, and it is expected to be applied to flat displays, amplification devices, microwave tubes, electron beam devices, vacuum measurement devices, and the like.

For example, in FIG. 7, the applicant of the present invention filed Japanese Patent Application No. 5-13.
FIG. 3 is a perspective view of a field emission type cathode 1 incorporated in an electron gun of a cold cathode type cathode ray tube filed by No. 3531, in which a large number of minute cold cathodes 3 are arranged in a pattern on a conductive base 2. The emitter area 4 (4R, 4G, 4B) for emitting electrons is formed on the base 2. still,
Reference numerals 4R, 4G, and 4B in the figure denote emitter areas that form three cathodes for R, G, and B of a color television or a color display.

As shown in FIG. 8, each of the micro cold cathodes 3 has a sharp tip shape made of a metal having a high melting point and a low work function, such as W and Mo, on a conductive substrate 2 such as Si. For example, a conical emitter electrode 5 is formed, and SiO 2 is formed around it.
An insulating layer 6 such as 2 is formed, and Mo, W,
The gate electrode 7 is made of a refractory metal such as Cr.

The micro cold cathode 3 having such a structure is manufactured by using a semiconductor manufacturing technique. For example, an insulating layer 6 and a gate electrode 7 are sequentially formed on a conductive substrate 2 made of Si or the like, and these are predetermined. The window is opened in a pattern, and the emitter electrode 5 is formed on the base body 2 of the window opening portion 8. The gate electrode 7 is provided in the opening 9 from the end edge of the window opening portion 8 of the insulating layer 6 to the opening 9. It is formed so as to project and is formed as a counter electrode for the emitter electrode 5.

When a voltage is applied between the gate electrode 7 and the emitter electrode 5 in the micro cold cathode 3 having such a structure, an electric field is concentrated at the sharp top end of the emitter electrode 5, and the electric potential difference from the top end to both electrodes is generated. A large amount of electrons are emitted in the direction of the arrow.
For example, when the diameter of the emitter electrode 5 is about 1 μm, the distance between the emitter electrode 5 and the gate electrode 7 is 50 to 1
When 00v voltage is applied, 1μA is applied from each micro cold cathode 3.
Some electrons are emitted.

Therefore, the field emission type cathode 1 has a high integration degree of several hundreds to several tens of thousands of minute cold cathodes 3 so that the electron beam value of about 300 to 500 μA necessary for the cathode current of the cathode ray tube can be obtained. It is formed by. The structure of the field emission type cathode 1 itself is known as a spindt type field emission type cathode device, and is used for a flat display device or the like.
The manufacturing method is disclosed in Japanese Patent No. 84325.

The cathode ray tube in which the field emission type cathode 1 is incorporated in the electron gun is a cold cathode type, and it is possible to achieve instant start-up and a long service life. Moreover, each micro cold cathode 3 is manufactured by a semiconductor manufacturing technique. It has the advantages that it can be manufactured with high density and high precision, and that the three cathodes for R, G, and B can be formed on the substrate 2 at the same time by accurately regulating the positions of the respective cathodes.

[0009]

However, as shown in FIG. 9, the field emission cathode 1 having such excellent characteristics is incorporated in the electron gun 10 and sealed in the neck 12 of the cathode ray tube bulb 11. The cold cathode type cathode ray tube 13 is created by scanning the electron beam L emitted from the electron gun 10 with the deflection yoke 15 mounted on the outer periphery of the funnel 14 and projecting it on the fluorescent film 17 on the inner surface of the face panel 16. When forming an image, the focus characteristic of the electron beam L was poor, and a clear image could not be obtained.

As a result of diligent investigations into the cause, the present inventor has found that the cause is as follows.

That is, in this type of field emission cathode, a large number of minute cold cathodes are arranged in a pattern on a conductive substrate, and an emitter area for emitting electrons is formed in a circular or square pattern on the substrate. However, the semiconductor manufacturing technique is used for the manufacture, and the micro cold cathodes have been formed by arranging them in a uniform distribution at equal intervals as compared with the conventional one.

Therefore, the field emission type cathode 1 is also shown in FIG.
As shown in the enlarged view of FIG. 0, the minute cold cathodes 3 are arranged in a circular pattern at equal intervals, and the emitter area 4 for emitting electrons is formed on the conductive substrate 2.

However, in the field emission type cathode 1 in which the minute cold cathodes 3 are arranged in a uniform distribution at equal intervals, the electron emission density becomes maximum in the central portion of the emitter area 4,
Gaussian distribution decreases toward the periphery. Therefore, the current density of the electron beam L emitted from the emitter area 4 is, as shown in FIG.
It decreases in a parabolic shape from the vicinity of the emitter area.

For this reason, the excitation light of the fluorescent film 17 onto which the electron beam L is projected can be seen clearly in the center of the beam L and has a dim spot light on the periphery, so that a clear image cannot be obtained. Particularly, in the peripheral portion of the panel 16, due to the distortion of the deflection magnetic field of the deflection yoke 15, the electron beam L is laterally flattened and the focus characteristic is further deteriorated.
A clear image could not be obtained.

In order to improve the focus characteristics of the electron beam L, it is conceivable to make the emitter area 4 small to make the electron beam diameter small, but the pitch between cones has a limit to narrow it, Also, if the pitch is reduced too much, there will be a problem with reliability.

Therefore, the present invention has been made in view of the problem of the focus characteristic of the field emission cathode, and a field emission cathode capable of obtaining the focus characteristic without lowering the brightness and obtaining a good image is obtained. Is intended.

[0017]

For this reason, the field emission cathode of the present invention has an insulating layer and a gate electrode sequentially formed on a conductive substrate, and a window opening portion of the insulating layer and the gate electrode on the substrate. A cone-shaped emitter electrode formed, and a plurality of micro cold cathodes that emit electrons from the window opening are arranged in a pattern, and an emitter area for electron emission is formed in a predetermined shape on the substrate. In the field emission cathode, the electron emission density of the emitter area is substantially uniform over the entire area, and the current density of the electron beam is substantially uniform from the center to the periphery of the emitter area. It is characterized by having done. Further, in the field emission type cathode of the present invention, the micro cold cathode is arranged so that the inner portion is lower in density than the peripheral portion of the emitter area, and the electron emission density is substantially uniform over the entire area. It has a feature. Further, in the field emission type cathode of the present invention, the micro cold cathode is set such that an electron emission characteristic is smaller in an inner portion than in a peripheral portion of the emitter area, and the electron emission density is substantially uniform over the entire area. Is characterized by. Further, in the field emission type cathode of the present invention, the electron emission characteristic is set by the window hole diameter of the gate electrode, the height of the emitter electrode, the cone angle of the emitter electrode, the work function of the emitter electrode, or the like which constitutes the micro cold cathode. It is characterized by that. Further, the field emission cathode of the present invention is characterized in that the emitter area is formed in a vertically long shape and emits an electron beam having a vertically long cross section.

[0018]

In the emitter area, the electron emission density is substantially uniform over the entire area, and the electron beam current density is substantially uniform from the central portion to the periphery of the emitter area. A sharp spot light can be obtained to the periphery of the beam without reducing the diameter. Therefore, good focus characteristics can be obtained and a clear image can be obtained. Further, since the micro cold cathode is formed so that the arrangement density in the emitter area or the electron emission characteristic is changed to make the electron emission density in the area substantially uniform, it is possible to easily obtain a desired characteristic by using semiconductor manufacturing technology. The product can be obtained and can be manufactured at low cost. Further, since the emitter area is formed in a vertically long shape and emits an electron beam having a vertically long section, the influence of the distortion of the deflection magnetic field in the peripheral portion of the screen is corrected, and good focus characteristics can be obtained over the entire screen.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a field emission type cathode 19 of the present invention. As with the field emission type cathode 1 of FIG. 6, a large number of minute cold cathodes 3 are formed in a circular pattern on a conductive substrate 2. The emitter areas 20 (20R, 20G, 20B) which are arranged and constitute three cathodes for R, G, B are formed on the base 2.

This field emission type cathode 19 is different from the field emission type cathode 1 in that the minute cold cathodes 3 on the conductive substrate 2 are arranged at a lower density in the inner area of the pattern of the emitter area 20 than in the peripheral area. However, the emission density of the electrons emitted from the emitter area 20 is only substantially uniform over the entire area surface. Other configurations are similar to those of the field emission cathode 1 shown in FIG.

FIG. 2 shows an arrangement pattern of the minute cold cathodes 3 of the field emission cathode 19.

That is, the micro cold cathode 3 is, as shown in the drawing,
The inner area of the pattern of the emitter area 20 is arranged at a low density with respect to the peripheral area, and the emission density of the emitted electrons is arranged to be substantially uniform over the entire area surface.

In the field emission type cathode 19 having such a structure, the number of electrons emitted inside the emitter area 20 is reduced as compared with that of the field emission type cathode 1 of FIG. 7, and it is incorporated in an electron gun of a cold cathode ray tube. The current density waveform of the electron beam L emitted from the emitter area 20 as shown in FIG.
The rectangular wave shape is substantially uniform from the central portion O to the peripheral portion.

Then, when the electron beam L having the rectangular current density waveform is projected on the fluorescent film 17 of the face panel 16, it becomes a spot light with a clear margin, and an image having excellent focus characteristics. Is obtained. In this case, since the electron beam L has a rectangular wave shape in its current density cross section, a clear spot light on the periphery can be obtained regardless of the size of the beam diameter. Therefore, the emitter area 20 is set to be large, and a sharp image with high brightness can be obtained with a thick electron beam.

FIG. 4 shows another embodiment of the present invention. Similar to the field emission type cathode 1 of FIG. 7, the micro cold cathodes 3 are arranged on the conductive substrate 2 in a circular pattern at equal intervals. , The base 2
A field emission type cathode 22 having an emitter area 21 for emitting electrons formed thereon.

This field emission type cathode 22 is different from the field emission type cathode 1 in that a plurality of micro cold cathodes 3 arranged in a pattern on a conductive substrate 2 are arranged in an emitter area 2.
The electron emission characteristic is set to be smaller in the inner part of the area than in the peripheral part of 1, and the emission density of the electrons emitted from the emitter area 21 is formed substantially uniformly over the entire area 21. Is the same as the field emission type cathode 1 of FIG.

That is, in the minute cold cathode 3 of the field emission cathode 22, the inner area of the emitter area 21 is compared with the peripheral area,
The window d of the opening 9 of the gate electrode 7 or the cone height h of the emitter electrode 5 shown in FIG. 5 is formed to be low, and the distance l between the gate electrode 7 and the emitter electrode 5 is set to be large. The emission characteristics of electrons are set to be small with respect to the gate-emitter bias voltage.

Here, in order to make the inner side of the emitter area 21 smaller than the peripheral side, the window hole d of the opening 9 or the cone height h of the emitter electrode 5 is made low, S
An insulating layer 6 and a gate electrode 7 are sequentially formed on the semiconductor substrate 2 such as i.
When the window hole d for forming the emitter electrode 5 is formed on the insulating layer 6 and the gate electrode 7 after the formation of the above, it is possible to easily manufacture by forming the inner side of the emitter area 21 into the small window hole d. can do.

In the field emission type cathode 22 having such a structure, the number of electrons emitted from the inner side of the emitter area 21 is reduced and the current density waveform of the electron beam L emitted from the emitter area 21 is reduced, as in the above embodiment. However, as shown in FIG. 3, a substantially uniform rectangular wave shape is formed from the central portion of the emitter area 21 to the periphery thereof, and the focus characteristic of the cathode ray tube can be improved.

In order to set the electron emission characteristic of the minute cold cathode 3 on the inner side of the field emission cathode 22 to be smaller than that on the peripheral side, the hole diameter d of the gate electrode 7 described above,
In addition to the cone height h of the emitter electrode 5,
It is possible to set a predetermined characteristic by the cone angle θ of, the work function of the emitter electrode 5 including the material and surface state of the emitter electrode 5, and the like.

FIG. 6 shows still another embodiment of the present invention. In the field emission type cathodes 19 and 22 of the above-mentioned respective embodiments in which the electron emission density is substantially uniform over the entire emitter area, the emitter area is A field emission type cathode 24 is shown in which 23 is formed in a vertically elongated shape such as a rectangle or an oblong shape.

Similar to the field emission cathodes 19 and 22, the field emission cathode 24 has the arrangement density in the area of the micro cold cathode 3 or the electron emission characteristic set in a predetermined manner.
The vertically elongated emitter area 23 is configured to emit an electron beam having a substantially uniform electron emission density.

When the field emission type cathode 24 having such a structure is incorporated in the electron gun 10 and mounted on the cathode ray tube 13, the electron gun 1
A vertically elongated electron beam L is emitted from zero. The vertically elongated electron beam L is generated by the deflection magnetic field of the deflection yoke 15 in the panel 1.
When deflected to the peripheral portion of 6, the deflection yoke 15 is distorted in the lateral direction due to the influence of the distortion. To project. Therefore, good focus characteristics can be obtained over the entire panel.

Although the present invention is applied to the electron gun of the cathode ray tube in the above embodiment, the present invention is not limited to this, and a plane for forming an image of a beam spot on the screen by projecting an electron beam on the fluorescent film. It is applied to a display or the like and has the same effect.

[0036]

As described above, according to the present invention, a large number of minute cold cathodes for emitting electrons are arranged in a pattern on a conductive substrate, and an emitter area for electron emission is formed in a predetermined shape on the substrate. In the field emission type cathode, the electron emission density in the emitter area is formed substantially uniformly over the entire area,
Since the electron beam current density is configured to be substantially uniform from the center of the area to the periphery, a clear beam spot can be obtained. Therefore, good focus characteristics can be obtained and a clear image can be obtained. Further, since the micro cold cathode is formed so that the arrangement density in the emitter area or the electron emission characteristic is changed to make the electron emission density in the area substantially uniform, it is possible to easily obtain a desired characteristic by using semiconductor manufacturing technology. The product can be obtained and can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view of a field emission cathode showing an embodiment of the present invention.

FIG. 2 is an arrangement pattern diagram of the micro cold cathode of FIG.

FIG. 3 is a current density distribution diagram of an electron beam obtained by the field emission cathode of FIG.

FIG. 4 is an arrangement pattern diagram of minute cold cathodes according to another embodiment of the present invention.

5 is a cross-sectional view of an essential part for explaining the dimensions of each part that determines the characteristics of the micro cold cathode arranged in FIG.

FIG. 6 is an arrangement pattern diagram of minute cold cathodes according to still another embodiment of the present invention.

FIG. 7 is a perspective view of a field emission type cathode which is a premise of the present invention.

FIG. 8 is a sectional view showing the structure of the micro cold cathode of FIG.

9 is a sectional view showing a schematic configuration of a cold cathode type cathode ray tube using FIG.

FIG. 10 is an arrangement pattern diagram of the micro cold cathode of FIG.

11 is a current density distribution diagram of an electron beam obtained by the field emission type cathode of FIG.

[Explanation of symbols]

 2 Substrate 3 Micro cold cathode 5 Emitter electrode 6 Insulating layer 7 Gate electrode 8 Window opening 19, 22, 24 Field emission cathode 20, 21, 23 Emitter area d Gate electrode window hole diameter h Emitter electrode height θ Emitter electrode Cone angle L electron beam

Claims (5)

[Claims] 1. A window comprising: an insulating layer and a gate electrode sequentially formed on a conductive substrate; and a cone-shaped emitter electrode formed on the substrate at a window opening portion of the insulating layer and the gate electrode. In a field emission type cathode in which a large number of minute cold cathodes that emit electrons from the dawn portion are arranged in a pattern, and an emitter area for electron emission is formed in a predetermined shape on the substrate, the emitter area is A field emission cathode, wherein the density is made substantially uniform over the entire area, and the current density of the electron beam is made substantially uniform from the center to the periphery of the emitter area. 2. The micro cold cathode is arranged such that the inner portion of the micro cold cathode is lower in density than the peripheral portion of the emitter area, and the electron emission density is substantially uniform over the entire area. 1. The field emission type cathode according to 1. 3. The electron emission characteristic of the micro cold cathode is set to be smaller in the inner portion than in the peripheral portion of the emitter area, and the electron emission density is substantially uniform over the entire area. Item 1. A field emission cathode. 4. The electron emission characteristic is set by a window hole diameter of the gate electrode, a height of the emitter electrode, a cone angle of the emitter electrode, a work function of the emitter electrode, or the like which constitutes the micro cold cathode. The field emission cathode according to claim 3. 5. The field emission type cathode according to claim 1, wherein the emitter area is formed in a vertically long shape and emits an electron beam having a vertically long cross section.