JP2783202B2 - Field emission type electron gun and control method thereof - Google Patents

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 electron gun.

[0002]

2. Description of the Related Art As a conventional field emission electron gun, a triode element has a sharp emitter electrode (cathode electrode) for concentrating an electric field, and a gate electrode and an anode electrode arranged in the vicinity thereof on a substrate. Is provided.

When a field emission type electron gun is used for a display device such as a flat panel, an anode electrode is arranged near a phosphor, and an electron beam emitted from the emitter electrode is emitted toward the phosphor. .

The characteristics of the emitter emission current I and the voltage V applied to the gate electrode are described in Fowler-Nordheim (FN).
Equation (1) showing the tunnel current of Fowler Nordheim)
Obey. In the following equation (1), A and B are constants, and φ is a work function.

[0005]

(Equation 1)

Meanwhile, in a high-quality display device, the ratio of the minimum luminance to the maximum luminance is required to be, for example, about 1,000.

In order to obtain this difference in luminance, a method of changing the amount of current from 1 to 1000 in a CRT is adopted.
In a plasma display or the like, an effective change in luminance is given by time division.

In a conventional display device such as a cathode ray tube, the relationship between the signal voltage E and the light output L is expressed by the following equation (2).
The gamma characteristic represented by

[0009]

(Equation 2)

Originally, such a characteristic should be corrected by the picture tube. However, it is specified that the signal is adjusted on the output side so as to be the γ-th power of the voltage amplitude V, and the input signal of the display device is determined. And the like, have a signal system that takes such gamma characteristics into consideration.

[0011]

In the case of a display device using a video signal having the above-mentioned γ characteristic in a field emission type electron gun, the current / voltage characteristic of the field emission type electron gun is the characteristic of Fowler-Nordheim (FN). Therefore, the video signal cannot be simply amplified by an amplifier or the like and operated as the gate voltage of the field emission electron gun.

Particularly, when the input signal is small, the output signal (emitter emission current) becomes large in the FN characteristic, and the difference from the γ characteristic becomes large. Therefore, in order to correct such a difference from the γ characteristic, it is necessary to provide a circuit for changing the characteristic or to implement a time-division operation method.

As described above, γ used in a conventional picture tube is
A display device using a signal having characteristics in a field emission electron gun has a problem that it cannot be applied to a field emission electron gun if the signal is simply amplified.

Accordingly, the present invention solves the above problems and provides a field emission type electron gun suitable for a display device by subjecting a signal having a γ characteristic used in a picture tube or the like to simple electric processing. The purpose is to:

[0015]

In order to achieve the above object, the present invention comprises a first gate electrode formed on a substrate and an emitter having a sharp tip. A second gate electrode is formed at a distance from the gate electrode, and an anode electrode is provided at a distance from the first and second gate electrodes. The emission current of the second gate electrode from the emitter is small. In this case, a field emission type electron gun is characterized in that bias control is performed so as to effectively suppress the voltage of the first gate electrode.

In the present invention, preferably, the second
A voltage proportional to the voltage of the first gate electrode is applied to the gate electrode, and the current-voltage characteristic in the low current region has an apparent γ characteristic.

According to the present invention, an assembly of a substrate and a plurality of sharp emitters having a first gate electrode is formed on the substrate, and a second gate electrode is provided above or around the first gate electrode. A method for controlling the formed field emission electron gun, wherein a value obtained by subtracting a predetermined voltage from a voltage of the first gate electrode with reference to a potential of the tip of the emitter, a voltage of the second gate electrode, , And a constant method regardless of the voltage of the first gate electrode.

According to the present invention, the emission characteristics of a plurality of emitter groups serving as emission sources of a field emission electron gun are improved by adding an auxiliary electrode.
By changing the electric field distribution near the emitter, converting the voltage of the gate electrode with a simple circuit and applying this to the second gate electrode, the emission characteristics follow the normal Fowler-Nordheim equation, In effect, the gamma characteristics are the same as those of the hot cathode. Therefore, according to the present invention, a video signal having a normal gamma characteristic can be immediately applied to a gate electrode or an emitter of a field emission electron gun by a simple circuit, and a time division control mechanism, a characteristic conversion circuit, and the like can be used. Is unnecessary, and the display device is simplified.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

[0020]

Embodiment 1 FIG. 1 is a cross-sectional view of the vicinity of an element for explaining a first embodiment of the present invention. Referring to FIG. 1, a sharp conical emitter 1 on a substrate 4 and a gate electrode (also referred to as a "first gate electrode") 2 made of a metal film
And a second metal film formed on the gate electrode 2.
Gate electrode 3 is provided.

These electrodes are provided with first and second insulating films 5,
6 are electrically separated from each other.

Further, a phosphor 7 and an anode electrode 8 are provided above the second gate electrode 3, a voltage Vg1 is applied between the emitter 1 and the gate electrode 2, and the emitter 1 and the second gate A voltage of Vg2 is applied to the electrode 3.

A voltage Va is applied between the anode electrode 8 and the emitter 1.

Electrons emitted from the tip of the emitter 1 by application of the gate voltage Vg 1 are decelerated by the second gate electrode 3, but accelerated by the voltage Va of the anode electrode 8 after passing through the second gate electrode 3. Then, it collides with the phosphor 7 and emits fluorescence.

The second gate voltage Vg2 is equal to the gate voltage Vg.
The value is set to a value smaller than g1, and when the amount of emission (the amount of emission current from the emitter) is small, the gate voltage is effectively suppressed.

FIG. 2 shows a current-voltage characteristic (gate voltage-emitter emission current characteristic) 9 (see a broken line) of this embodiment, a γ characteristic 10 when a hot cathode is used, and a second gate electrode 3.
-Voltage characteristics 11, 1 when the voltage applied to
2 and 13 are each shown in double logarithms.

Here, Voff is a voltage at which the emission is so small that an image cannot be seen. Further, the second gate voltage Vg2 is reduced from the case of the current-voltage characteristics 11 to the case of 13 (V11>V12>, where the voltages of the second gate electrodes 3 of the characteristics 11 to 13 are V11, V12 and V13). V13).

As is clear from FIG. 2, the current-voltage characteristic 1
In Examples 1, 12, and 13, the emission (emission) current amount of the field emission type electron gun is large in the low current region.

However, when the second gate electrode 3 is provided, the second gate voltage Vg2 is changed to Vg2 = α · (Vg
1-Vo), as shown in the current-voltage characteristic 9, the electric field is suppressed in the low current region, the emission of electrons is suppressed, the apparent γ characteristic is obtained, and the γ characteristic 10 in the case of the hot cathode is parallel. It has become. Where α and V
o is constant and can be easily configured by a resistor and a constant voltage power supply.

That is, the second gate voltage Vg2 increases as the gate voltage Vg1 increases. For example, the characteristic curves 12, 11 are obtained from the voltage-current characteristics shown by the characteristic curve 13 in FIG.
(See the characteristic curve 9 shown by the broken line), and as a result, the second gate voltage Vg2 effectively causes the gate voltage Vg1 to have the γ characteristic.

[0031]

[Embodiment 2] FIG. 3 is a sectional view showing the vicinity of an element according to a second embodiment of the present invention. Referring to FIG. 3, the second gate electrode 3 made of a metal film is located above the substrate, but is not integrated with the substrate, and like the anode electrode 8 and the like,
It is integrated with a vacuum device such as a glass tube. The gate electrode 2, the second gate electrode 3, the anode electrode 8 and the like are biased in the same manner as in the first embodiment.

[0032]

Third Embodiment FIG. 4 is a sectional view showing the vicinity of an element according to a third embodiment of the present invention. Referring to FIG. 4, second gate electrode 3 made of a metal film is arranged on insulating film 5 below gate electrode 2 so as to surround gate electrode 2.

In the embodiment described above, the emitter is projected on the main surface of the substrate and sharpened.
The emitter material and the shape of the emitter are not limited to those described above, and a similar effect can be obtained with a sharp ring-shaped emitter, a planar emitter, or a structure that emits current laterally (emission). Further, the positions of the anode and the phosphor can be arbitrarily selected.

[0034]

As described above, according to the present invention, the emission characteristics of a plurality of emitter groups serving as emission sources of a field emission type electron gun are improved by adding an auxiliary electrode.
By making the electric field distribution in the vicinity of the emitter variable, the gate electrode voltage is converted by a simple circuit and applied to the second gate electrode, so that the emission characteristic is effectively changed from the characteristic according to the usual Fowler-Nordheim equation. It has the same gamma characteristics as the hot cathode.

Therefore, according to the present invention, a video signal having a normal gamma characteristic can be immediately applied to a gate electrode or an emitter of a field emission type electron gun by a simple circuit. A conversion circuit or the like is not required, and simplification of the display device is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view for explaining a first embodiment of the present invention.

FIG. 2 is a diagram showing characteristics of the first embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view for explaining a second embodiment of the present invention.

FIG. 4 is a schematic sectional view for explaining a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Emitter (group) 2 Gate electrode 3 2nd gate electrode 4 Substrate 5 Insulating film 6 Insulating film 7 Phosphor 8 Anode electrode 9 Current-voltage characteristic of the present invention 10 Current-voltage characteristic of hot cathode 11-13 Current-voltage characteristics when constant voltage is applied

Claims (5)

(57) [Claims] A first gate electrode formed on a substrate;
An emitter having a sharp tip is formed, a second gate electrode is formed at a distance from the first gate electrode, and an anode electrode is arranged at a distance from the first and second gate electrodes. A field emission type electron gun, wherein the second gate electrode is bias-controlled so as to effectively suppress the voltage of the first gate electrode when the emission current from the emitter is small. 2. A voltage proportional to a voltage of the first gate electrode is applied to the second gate electrode,
2. The field emission type electron gun according to claim 1, wherein the current-voltage characteristic in a low current region has an apparent γ characteristic. 3. The semiconductor device according to claim 2, wherein the second gate electrode is disposed on the same substrate as the substrate on which the first gate electrode is formed, while being electrically insulated from the first gate electrode. A field emission type electron gun according to claim 1. 4. The field emission electron gun according to claim 1, wherein said second gate electrode is separated from said substrate and arranged integrally with a vacuum device. 5. An assembly of a substrate and a plurality of sharp emitters having a first gate electrode formed on the substrate, and a second gate electrode formed above or around the first gate electrode. A method of controlling a field emission type electron gun, wherein a value obtained by subtracting a predetermined voltage from a voltage of the first gate electrode with reference to a potential of the tip of the emitter;
Wherein the ratio of the voltage of the gate electrode to the voltage of the first gate electrode is constant regardless of the voltage of the first gate electrode.