JPS5836460B2 - electron source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron source used in a flat image display device for displaying characters, images, etc.
The object of the present invention is to provide a large-area, substantially flat, uniform electron source.

As electron sources for cathode ray tubes, various materials and configurations have been proposed so far, such as strong field emission, photoelectron emission, secondary electron emission, and thermionic emission.

Regarding linear thermionic emission sources, an electron source for a flat plate CRT, as proposed in US Pat. No. 3,935,500, has been proposed and commercialized as an electron source for fluorescent display tubes.

Furthermore, there is a method proposed by us in Japanese Patent Application No. 53-51810 (Japanese Unexamined Patent Publication No. 54-143063).

Electron sources for fluorescent display tubes have a structure in which an electron beam is extracted over a sufficient area from a single thermionic emission cathode ray, and a voltage is applied to the electron beam extraction electrode to emit an almost uniform electron beam over the required range. Figure 1 A
, B shows the case where there is one cathode ray.

Electrons as indicated by arrows are emitted from the cathode ray 1 and head toward the electron beam extraction electrode 2.

The distribution of the amount of electron beam at this time is shown by a hatched area 3 surrounded by a mountain-shaped solid line.

The dotted line in FIG. 1B indicates the case where there is only one cathode ray.

As is clear from this, the range in which a substantially uniform distribution can be obtained is limited.

Therefore, it is difficult to realize a substantially uniform flat electron source.

In particular, it is extremely difficult to achieve a uniform distribution in the portion where the electron beams from adjacent cathode rays overlap.

The electron source for a flat CRT proposed in US Pat. No. 3.935.500 has a problem in that its power consumption is extremely high, making it impractical.

The specification of Japanese Patent Application No. 53-51810 that we proposed earlier (
FIG. 2 shows an electron source disclosed in Japanese Patent Application Laid-Open No. 54-143063.

21 is a wire-like thermal electrode, and the surface of a tungsten wire, usually several tens of microns in diameter, is coated with an oxide electron emitting material.

22 is a cylindrical electrode with a U-shape and a U-shape, and is a back electrode for the linear hot cathode 21.

23 is an extraction electrode for extracting an electron beam, and is electrically insulated from the cylindrical electrode 22, and has a series of multiple through holes 1 or slit-like through holes corresponding to the linear cathode 21. A hole 24 is provided.

Reference numeral 25 denotes an electrode for accelerating the electron beam that has passed through the through hole 24.

One end of the linear hot cathode 21 is connected to the positive electrode of the power source V1 via a low resistance R.

The other end of the linear hot cathode 21 is connected via a diode 26 to the negative electrode of the power source 1.

27 is a negative pulse voltage generator.

A negative voltage is applied to the cylindrical electrode 22 by the power source 2, and the electrode 2
Positive voltages are applied to power supplies 3 and 25 by power supplies 3 and 4, respectively.

When the linear hot cathode 21 is powered by the power source 1, the hot cathode 21 becomes in a state where it can emit electrons, but even though a positive voltage is applied to the electrode 23, a negative voltage is applied to the cylindrical electrode 22. Electrons are not emitted because voltage is applied.

In other words, it can be considered that a bias voltage is applied to the electrode 22 to prevent electron emission.

However, in this state, when a negative pulse voltage is applied to one end of the hot salt electrode 21 by the pulse voltage generator 27, the linear hot cathode 21 becomes negative and electron emission occurs.

At this time, the diode 26 is in the opposite direction at the other end of the hot cathode 21, so that the potential difference between both ends of the hot cathode becomes approximately O, and there is no potential gradient in the axial direction.

Therefore, it is possible to obtain an electron beam that is uniform and has a high current density.

However, this electron source has a drawback that it cannot be used as an electron source that emits a uniform electron beam over a large area and in a flat plate shape.

In order to make this linear cathode large in area, it has to be stretched extremely long, which increases the resistance of the linear cathode itself and the electron emission current emitted from it. This is because even if the potential gradient is eliminated, a non-negligible potential gradient is generated at both ends of the linear cathode due to the resistance and current of the linear cathode.

As described above, conventionally, there has been an extremely difficult problem in realizing a substantially planar uniform electron source over a large area using a linear thermionic emission source.

The present invention solves the above-mentioned drawbacks and problems, and provides an electron source that can obtain a uniform electron beam having a substantially planar shape over a large area.

FIG. 3 shows a top view of the arrangement of the linear hot cathodes and the positions of the through holes of the extraction electrodes.

Here, a single solid line represents a linear hot cathode, and a rectangular frame represents a through hole.

A 1 p A 2 s A 3 , ”゜゜A ne
An+1・・・・・・・・・Arbitrary two columns A n m
At A n + 1, a linear hot cathode is used. An column is A
nBmpAnB m + 1, = A n + 1
Column is An+IBm, An+I Bm+1p An+I
Bm+2, A
n, A n + 1 rows of linear hot cathodes are arranged discontinuously and alternately.

Of course, it is also possible that there is only one linear hot cathode in one row.

In order to extract electrons from the linear hot cathode arranged in this manner, an extraction electrode provided with a through hole is arranged at the bottom.

The potential difference between both ends of each of the linear hot cathodes is set to zero, and the extraction electrodes are set at a relatively positive potential, so that electrons are extracted toward the extraction electrodes.

A pair of deflection electrodes is arranged below the extraction electrode in correspondence with the position of each linear cloud pole to deflect the electrons that have passed through the through holes.

The deflection range is the shaded area P ns P n + in Fig. 3.
As shown in 1, the electron beam emitted from the hot cathodes in the An array is A
An+1 from the vicinity of the line directly below the linear hot cathode of the n-1 row
It is deflected near the line 1 directly below the linear hot cathode in the row.

As a result, the potential gradient caused by the linear hot cathode itself can be made negligibly small, and a uniform electron beam having a substantially flat plate shape can be obtained over the entire area.

By electrically connecting the linear hot cathodes arranged in one row in parallel, it is possible to prevent an increase in the resistance of the linear hot cathodes and to further reduce the potential gradient caused by the linear hot cathodes themselves. This makes it possible to obtain an extremely uniform electron beam.

A specific embodiment of the present invention will be described in detail with reference to FIG.

The substantially planar uniform electron source has a size of approximately 750 mm in length.
It has a configuration in which linear hot cathodes measuring approximately 150 mm wide and 150 mm wide are arranged, 4 horizontally and 30 vertically, as shown in FIG.

A partial perspective cross-sectional view is shown in FIG.

The wire diameter is 20μφ and the length is 1701! A linear hot cathode 41 in which a thermionic emission material such as barium oxide is electrodeposited on a tTIL tungsten wire 40 is stretched over a hot cathode support plate 42 .

The hot cathode support plate 42 is made of a thin metal plate, and due to its own spring action, the short linear hot cathode 41 is always stretched in a straight line without loosening.

The electron beam extraction electrode 43 is a metal plate with a thickness of 200 μm, and has a through hole 44 with a slit width of about 500 μm.

The linear hot cathode 41 is placed about 2 mm apart from the electron beam extracting electrode 43 and directly above the through hole 44 .

The hot cathode support plate 42 and the electron beam extraction electrode 43 are connected by frit glass and are insulated from each other.

A pair of electron beam deflection electrodes 45 are arranged about three plates apart from each other and are installed under the electron beam extracting electrode 43 and corresponding to the through holes 44 about one plate apart.

This electron beam deflection electrode is supported by a frame made of an insulator.

An example of a method of operating this electron source will be described.

l-pole support plate 42 which becomes both terminals of the linear hot cathode located one row above.
A current of approximately 200 mA is passed between two lead wires 46 electrically connected in parallel to maintain a state in which the hot electrons can be emitted from the linear hot cathode 41 at all times.

A diode is connected to one electrode in the opposite direction so that when a negative pulse voltage is applied to both ends of the linear hot cathode 41, the both ends have approximately the same potential.

In this state, the pulse width is 1 msec and the repetition frequency is 60
Hz, negative pulse voltage of -10V peak value is connected to the lead wire 46.
+5 to +I to the electron beam extraction electrode 43.
When a voltage of approximately OV is applied to one side between the pair of seat breaks 47 of the electron beam deflection electrode 45 and a voltage of +50V to the other, the electron beam passes through the through hole of the electron beam extraction electrode and the deflection electrode At this point, the voltages are simultaneously deflected in a line in the direction of the +100V side electrode.

At this time, the current emitted from each linear hot cathode is several mA, and based on this, the potential difference between the two ends of one linear hot cathode is less than 1 μ, and an extremely uniform electron beam is emitted. become.

Further, by sequentially changing the deflection voltage of the deflection electrode, the electron beam sweeps the surface uniformly in a linear manner.

Then, by sequentially applying the negative pulse voltage to the linear hot cathodes of each row and simultaneously changing the deflection voltage sequentially in synchronization with the negative pulse voltage, a uniform electron beam is swept across a large area. I can do it.

This makes it possible to provide a substantially flat, uniform electron source with a large area.

Furthermore, the electron beam deflection electrode may be placed in front of the electron beam extraction electrode.

The twisted linear hot cathodes in one row may be electrically connected in series.

1. A continuous linear electron beam is obtained by simultaneously applying a negative pulse voltage to two rows of linear hot cathodes adjacent to each other, and by simultaneously deflecting the electron beam, a uniform planar electron source is obtained. It is also possible.

[Brief explanation of the drawing]

Figures 1A and 1B are diagrams showing the state of electron emission from cathode rays,
FIG. 2 is a perspective view of a conventional electron source, FIG. 3 is an explanatory diagram of the electron source of the present invention, and FIG. 4 is a partial perspective view showing an embodiment of the electron source of the present invention. 40... Tungsten wire, 41... Mercenary hot cathode, 42... Hot cathode support plate, 43...
...Electron beam extraction electrode, 44...Through hole,
45...Electron beam deflection electrode, 46.47...
····Lead.

Claims (1)

[Scope of Claims] 1 In each row, linear hot cathode portions are disposed discontinuously, and the linear hot cathode portions are relative to each other between adjacent rows of the linear hot cathode portions on any one of the vertical lines. A linear hot cathode consisting of a plurality of rows arranged so as not to face each other, and a through hole formed corresponding to the linear hot cathode portion, and an electron beam extractor for extracting electrons from the linear hot cathode. An electron source comprising an electrode and deflection electrode means corresponding to the through hole and deflecting an electron beam to a position parallel to the linear hot cathode. 2. The electron source according to claim 1, wherein at least one row of linear hot cathode sections are electrically connected in parallel.