JP3068434B2 - Electron gun - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun as a solid-state electron beam generator in which a plurality of electron-emitting devices are arranged.
In particular, the present invention relates to an electron gun capable of easily controlling the amount of emitted electrons.

[0002]

2. Description of the Related Art A conventional electron gun is configured as a triode. As shown in FIG. 9, a conceptual diagram shows a filament 111, a grid 112, and a collector (plate) 113.
And the grid 11 with respect to the filament 111
By applying a voltage from the control voltage source 114 to the collector 2 and the collector 113, electrons are emitted from the filament 111 toward the collector 113. At this time, the filament 11
By controlling the voltage between 1 and the grid 112, the amount of emitted electrons is controlled.

On the other hand, recently, an electron gun configured as a solid-state electron beam generator has been proposed, and its application has been expanded. As shown in FIG. 10, the electron gun has an insulating film 212 provided on a substrate 211 made of a semiconductor layer formed on an upper surface of a cathode electrode (not shown), and a gate 213 provided on the insulating film. . Then, a conical emitter 215 is provided in the opening 214 provided in the insulating film 212 and the gate 213. Further, a collector 216 is provided to face the emitter 215. And
By applying a potential from the control voltage source 217 between the substrate 211 (emitter 215), the gate 213, and the collector 216, the emitter 215, the gate 213, and the collector 216 are applied.
Electrons are emitted from the emitter 215 by the electric field between them. At this time, the amount of emitted electrons is controlled by controlling the voltage applied between the emitter and the gate.

[0004]

In such a conventional electron gun, the amount of emitted electrons is controlled by controlling the applied voltage. In any case, the electron gun has a triode structure in principle. For this reason, the current is changed in proportion to the control voltage in the 5/2 power, and the amount of electrons emitted from the electron gun is changed in an analog manner in accordance with the control voltage.
In particular, in this type of electron gun, the amount of current fluctuates, which makes the amount of emitted electrons unstable. Further, when a request is made to digitally control the amount of emitted electrons, such as when an electron gun is applied to a digitized electronic device in recent years, there is a problem that it is difficult to satisfy the request.

To solve such a problem, see, for example,
In Japanese Patent No. 249026, a constant current element is connected to each electron gun to stabilize the amount of emitted electrons due to current fluctuation. However, this configuration is effective in controlling the amount of emitted electrons to be constant, but cannot change the amount of emitted electrons digitally. Japanese Patent Application Laid-Open No. 63-153585 discloses an electronic gun having a different amount of emitted electrons, and digitally controls the amount of emitted electrons by combining them. However, in order to widen the control range of the amount of emitted electrons, it is necessary to manufacture many types of electron guns having different sizes and characteristics, which causes a problem that the structure becomes complicated and the manufacturing process becomes complicated. .

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electron gun capable of digitally and stably controlling the amount of emitted electrons, while simplifying the structure and facilitating manufacture. It is in.

[0007]

In the electron gun of the present invention, a plurality of electron-emitting devices driven at a constant current are grouped as electron gun groups of different numbers, and each electron gun group is individually or in plural. Are simultaneously selected and driven.

The electron-emitting devices divided into groups are
Arranged on the same plane, the center position of each group is almost straight
Preferably, it is arranged on top.

The electron-emitting devices divided into groups are
The electron-emitting devices of each group are arranged on the same plane.
Preferably, they are arranged in a concentric manner.

[0010] The electron-emitting device may be a substrate such as a semiconductor layer.
A gate formed thereover via an insulating film,
An emitter provided on the substrate in the opening of the gate and gate.
And a collector arranged opposite to the emitter.
And the collector arranged opposite to the emitter
Split and supply constant current individually to each divided collector
Configuration.

[0011]

By emitting a different number of electron-emitting devices, that is, each electron gun group divided by micro electron guns at a constant current, the amount of emitted electrons of each electron gun group is proportional to the number of micro electron guns. Becomes Therefore, by individually selecting or driving a plurality of electron gun groups simultaneously, it is possible to perform control in which the amount of emitted electrons is digitally changed.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual configuration diagram showing a reference example of the present invention.
In the present embodiment , the electron gun 1 is composed of a large number of micro electron guns 10, and the total amount of emitted electrons can be controlled to change from 1 unit to 15 units in one unit step. An example is shown. Here, the micro electron gun 1
As shown in FIG. 2, the cross-sectional structure itself is the same as that of a conventional electron gun as a solid-state electron beam generator, and an insulating film 1 is formed on a substrate 11 made of a semiconductor layer or the like.
2. A gate 13 is formed, and a conical emitter 15 is formed in an opening 14 provided in the insulating film 12 and the gate 13.
Is formed. The emitter 15 is connected to the constant current circuit 2 and applies a voltage from the control voltage source 4 to the constant current circuit 2 via the drive circuit 3 as a switch circuit controlled by the control signal SC. It is configured such that a predetermined constant current is supplied to the emitter 15 of the electron gun 1. The constant current circuit 2 may have a configuration in which a diode as a constant current element is connected to the emitter, as described in, for example, Japanese Patent Application Laid-Open No. 4-24926.

In FIG. 1, an electron gun 1 has a plurality of micro electron guns 10 arranged and formed on the same substrate, of which one, two, four, eight
Each of the electron gun groups G1, G2, G3, G4
In each electron gun group, each micro electron gun can be driven simultaneously. The electron gun groups G1 to G4 are collectively connected to the drive circuit 3 for each group. In the drive circuit 3, any one of the electron gun groups,
Alternatively, a plurality of electron gun groups are selected at the same time, the control voltage 4 is applied, and a constant current is supplied via the constant current circuit 2 to each micro electron gun in the group.

In this embodiment , an analog control signal SC for controlling the amount of emitted electrons is input to the A / D converter 5,
The A / D converter 5 converts the control signal SC into a digital signal, which is converted into a coded signal, in this case, a BCD signal that is coded as a binary code. Then, by inputting the digital signal to the drive circuit 3, each of the electron gun groups G1 to G4 is selected and the constant current circuit 2 is selected.
Is turned on to supply a constant current to each of the micro electron guns in the selected group. The control voltage 4 is set in advance so as to emit a predetermined amount of electrons when applied to each micro electron gun 10 through the constant current circuit 2. Specifically, the value is set to a value that allows a current of 1 microamp per microelectron gun to flow.

An example of controlling the amount of emitted electrons by the electron gun having the above configuration will be described. Here, it is assumed that all the small electron guns are set to operate at a constant current of 1 microampere. When the analog control signal SC is 0, A / D
The coded output of the converter 5, here each output of 4 bits, is all 0, and any of the electron gun groups G1-G
4 also switches off. Therefore, the electron emission amount is 0
Becomes When an analog signal is input such that only one bit of the LSB, which is the minimum output of the A / D converter 5, is turned on, each micro electron gun 10 of the electron gun group G1 corresponding to the LSB is turned on. , Microamps 1 are emitted.

When the analog input voltage at the next stage increases, only the electron gun group G2 is turned on, and electrons of the current of the microamp 2 are emitted. next,
The electron gun group G1 and the electron gun group G1 are switched on, and the electron emission of the microamp 3 current is performed. Next, only the group G3 is switched on, and the electron emission of the current of the microamp 4 is performed. Hereinafter, one, two, or three of the electron gun groups are selected. When the current amount is the maximum, all the four electron gun groups are switched on, and the electron emission of the current of the microamp 15 is performed. This makes it possible to digitally control the amount of emitted electrons from microamp 1 to microamp 15 for each microamp unit.

In this reference example , each micro electron gun 10
Since the constant current circuit 2 is provided in each of the emitters 15, the current amount of each micro electron gun can be accurately determined, and the linearity of the electron amount emission amount by digital control,
The stability can be improved, and the above-mentioned digital control of the amount of emitted electrons can be performed with high accuracy.

Here, in the constant current circuit of the micro electron gun, it is not necessary that all the micro electron guns have the same value, the number of the micro electron guns is the same for each electron gun group, and the constant current circuit connected to each micro electron gun Even if the current value of the current circuit is changed so as to constitute, for example, a power of n, it is possible to control the amount of emitted electrons to be different for each electron gun group as in the above-described embodiment . In particular, in applications where the amount of current drawn is extremely small, this configuration can reduce the area occupied by the emitter. Further, by changing the number of micro electron guns belonging to each electron gun group, it is possible to increase the maximum electron amount or increase the division ability arbitrarily.

Alternatively, as shown in FIG. 3, each of the electron gun groups G1 to G4 is connected to one constant current circuit 21 to 24 for each group, and the constant current circuits 21 to 24 are switched by the drive circuit 3. By doing so, the current supply to each of the electron gun groups G1 to G4 may be selected. With this configuration, the number of constant current circuits can be reduced as compared with the case where a constant current circuit is connected to each micro electron gun as in the above reference example , and the overall circuit scale can be reduced. it can.

As shown in FIG. 4, the gates 131 to 13 of the micro electron guns 10 in each of the electron gun groups G1 to G4.
4 are integrally formed, and the gate 131 of each electron gun group is formed.
The drive circuit 3 may be used to select the voltage to be applied to .about.134 to emit electrons for each electron gun group. With this configuration, in a normal micro electron gun, the emitter is connected to the substrate side, so there is no place to provide a complicated circuit, but since the gate is on the substrate, the control circuit is arranged around the chip. It is also possible to reduce the size of the electron gun by integrally configuring the A / D converter and the drive circuit.

Further, as shown in FIG. 5, the number of the small electron guns 10 in each of the electron gun groups G11 to G14 is
The number of electron gun groups G1 to G4 of the reference example is twice as many as that of the reference example.
Two micro electron guns may be used, and another half micro electron gun may be configured as a spare electron gun. This way,
When the micro electron gun is destroyed, another micro electron gun can be used, and the redundancy can be increased. Also,
By alternately using 1/2 micro electron guns, the overall life of each micro electron gun can be extended. In some cases, by operating all of the small electron guns in each electron gun group, the control range of the amount of emitted electrons can be further expanded.

In this example, the number of micro electron guns in each electron gun group is not limited to two times as shown in the figure, but can be set to three times or more times. When the size is very large, the effect becomes remarkable. With current semiconductor technology, millions of micro electron guns can be made in 1 mm square,
In the case of digital control of about it, the size of the multiple can be set to about 10,000.

FIG. 6 is a diagram schematically showing an embodiment of the present invention. In the present embodiment, the emitter 1 constituting the micro electron gun
5 and a plurality of collectors 16 opposed to each other, here 3
The collectors 161 to 163 are divided into constant current circuits 211 to 163, respectively.
213 and connect each constant current circuit to the drive circuit 3
Are configured to be selected one by one or simultaneously. According to this configuration, the amount of emitted electrons can be controlled in accordance with the number of collectors that supply a constant current.
The control can be performed in units of one step up to the unit. Further, in this configuration, since it is not necessary to connect a constant current circuit to the emitter of the micro electron gun, the structure of the micro electron gun can be simplified.

Here, in the present invention, the change control of the amount of emitted electrons is performed by dividing a large number of micro electron guns into a plurality of groups and changing the selection thereof. When the selection of each of the small electron guns is changed, that is, when the luminance is changed, the center position of the distribution of the emitted electron flow is changed accordingly. For this reason, when an electron gun is actually applied to various electronic devices,
A deflection circuit is required to correct the change in the center position of the electron flow, but if the change in the center position is not regular, the correction by the deflection circuit is also difficult.

Therefore, in the arrangement of each of the electron gun groups G1 to G6 having the number arrangement of the small electron guns shown in FIG. 7, the center position of the spatial distribution of the electrons emitted from the electron guns is linear with respect to the luminance. The arrangement is made to move. Therefore, when the brightness is increased by deflecting the selection of the micro electron gun,
Along with this, the distribution center of the emitted electrons changes from upper left to lower right. Therefore, by operating the deflection circuit so as to apply a constant offset to the luminance, it is possible to realize a preferable correction.

On the other hand, in the arrangement of the electron gun groups G21 to G23 comprising the micro electron guns shown in FIG.
Are arranged so as to form concentric circles while forming N-ary elements. With this configuration, the distribution center of the emitted electrons is not changed even when the luminance changes, so that it is not necessary to correct the deflection with respect to the luminance. In an electronic device that does not perform deflection, the electron flow can always be fixed at a fixed position, and the quality and reliability of the electron gun can be improved.

[0027]

As described above, according to the present invention, a plurality of electron-emitting devices driven at a constant current are divided into groups each having a different number of electron guns. Since it is configured to be selected and driven, the amount of emitted electrons of each electron gun group is proportional to the number of micro electron guns, and control is performed by digitally changing the amount of emitted electrons according to the selection. It becomes possible. In this case, since the electron-emitting devices have the same configuration, the configuration of the electron gun can be simplified, and the electron gun can be easily manufactured.

Further, by driving the grouped electron-emitting devices with a constant current in group units, the number of constant current sources can be reduced and the configuration can be simplified.

Further, according to the present invention, the number of electron-emitting devices belonging to each group is different for each integral multiple of the power of n, so that the amount of emitted electrons can be digitally controlled for each minimum unit. Becomes

Further, by arranging the grouped electron-emitting devices on the same plane and arranging the center position of each group on a substantially straight line, when the amount of emitted electrons is controlled to change, the center of the electron distribution is controlled. Can be deflected simply by correcting in a certain direction, and the deflection control is facilitated.
In particular, by arranging the electron-emitting devices of each group concentrically, it is not necessary to deflect the center of the electron distribution.

In particular, in the present invention, the above-mentioned electron-emitting device includes a gate formed on a semiconductor layer via an insulating film, and an emitter provided on the semiconductor layer in an opening of the insulating film and the gate. A solid-state electron beam generator composed of a collector arranged opposite to the emitter and supplying a constant current to the gate,
Since the board is on the board, A / D conversion occurs around the chip.
Control circuits such as a converter and a drive circuit.
Thus, the size of the electron gun can be reduced. Alternatively, by dividing the collector into a plurality of parts and supplying a constant current to each of the divided collectors individually, it becomes possible to perform an on / off operation of electron emission in the electron-emitting device.

According to the present invention, it is possible to prevent the destruction of the electron-emitting devices, the noise caused by the fluctuation of the current in each electron-emitting device, and the deterioration of the performance due to the unevenness of the emission current values. In addition, the current value can be controlled with a very low voltage enough to drive a digital switch, the power consumption can be significantly reduced compared to conventional electron guns, and the output load of the drive circuit can be significantly reduced. , High-speed operation becomes possible. Since control can be performed not only by an analog signal added from the outside but also by a digital signal, it is possible to obtain effects such as realization of a future digital control electron gun.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram of a reference example of an electron gun of the present invention.

FIG. 2 is a sectional view showing an example of a micro electron gun according to the present invention.

FIG. 3 is a conceptual configuration diagram of a modification of the reference example of the present invention.

FIG. 4 is a conceptual configuration diagram of another modification of the reference example of the present invention.

FIG. 5 is a plan view showing a modification of the configuration of the electron gun group according to the reference example of the present invention.

FIG. 6 is a cross-sectional configuration diagram showing a conceptual configuration of an embodiment of the present invention.

FIG. 7 is a plan view showing a modification of the arrangement of the electron gun groups according to the present invention.

FIG. 8 is a plan view showing another modification of the arrangement of the electron gun groups according to the present invention.

FIG. 9 is a conceptual sectional view showing a configuration of a conventional electron gun.

FIG. 10 is a conceptual sectional view showing another example of the conventional electron gun.

[Explanation of symbols]

 Reference Signs List 1 electron gun 2 constant current circuit 3 drive circuit 4 control voltage source 5 A / D converter 10 micro electron gun 11 substrate 12 insulating film 13 gate 15 emitter 16 collector G1 to G4 electron gun group

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-272638 (JP, A) JP-A-4-249026 (JP, A) JP-A-56-35182 (JP, A) JP-A-51- 42464 (JP, A) JP-A-3-295138 (JP, A) JP-A-6-67621 (JP, A)

Claims (3)

(57) [Claims] 1. An electron gun having a plurality of electron-emitting devices, wherein each of the electron-emitting devices is driven at a constant current, wherein the plurality of electron-emitting devices are grouped as different numbers of electron gun groups, respectively. The group is configured to be individually or plurally selected and driven at the same time, and the electron-emitting device includes a gate formed on a substrate such as a semiconductor layer via an insulating film; And an emitter provided on the substrate in the opening of the gate, and a plurality of divided collectors arranged opposite to the emitter, and a constant current is individually supplied to each of the divided collectors. An electron gun. 2. The electron gun according to claim 1, wherein said grouped electron-emitting devices are arranged on the same plane, and the center position of each group is arranged on a substantially straight line. 3. The electron gun according to claim 1, wherein the grouped electron-emitting devices are arranged on the same plane, and the electron-emitting devices of each group are arranged concentrically.