JPH04312752A - Electron tube device - Google Patents

Abstract

PURPOSE:To provide a vidicon tube device which can be sufficiently decreased in the aperture so that high resolving power of an image can be realized and a service life can be lengthened. CONSTITUTION:In an electron tube device equipped with an electron beam source 1 which produces an electron beam, electroptic systems 3, 4, 5 which focuses and deflects an electron beam EB and a target 7 scanned by the deflected electron beam EB, the electron beam source 1 is of a field emission type. That is, this electron beam surface 1 includes a substrate 11, a sharp cathode 12 installed projected from the substrate 11, and a control electrode 14 installed on the substrate 11, as insulated from this cathode 12 and a potential difference exceeding a threathhold value where field emission of an electron from the cathode 12 may occur is provided between the cathode 12 and the control electrode 14 only in a period other than the fly-back line period of scanning by the electron beam EB.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron tube device, and more particularly, it is used in an image pickup tube such as a vidicon.

0002

2. Description of the Related Art Conventionally, a hot cathode has been used as the cathode of a vidicon. However, in this case, the initial velocity distribution of emitted electrons is large, and afterimages are likely to occur. In addition, since a heater is used, the temperature of the target tends to rise.
There was a drawback that the dark current increased.

[0003] As an electron tube (for example, a cathode ray tube) aimed at eliminating such drawbacks, Japanese Patent Application Laid-Open No. 63-13644
The one shown in No. 3 is known. Here, a liquid metal such as Ga-In-Sn is used as an electron emission source. According to this, there is no need to use a heater, and it is also possible to reduce the beam diameter.

0004

However, with the above-mentioned prior art, it is necessary to prepare liquid metal, and it is also difficult to achieve a sufficient reduction in the beam diameter.

[0005] The present invention has been made in consideration of the above circumstances, and it is possible to reduce the beam diameter to a sufficiently small size at low cost, and therefore, it is possible to achieve high resolution of images.
Moreover, it is an object of the present invention to provide an electron tube device that can have a long life.

[0006]

[Means for Solving the Problems] An electron tube device according to the present invention includes an electron beam source that generates an electron beam, an electron optical system that focuses and deflects the electron beam, and a target that is scanned by the deflected electron beam. The above electron beam source includes a substrate, a sharp cathode provided protruding from the substrate, and a control electrode provided on the substrate and insulated from the cathode, and between the cathode and the control electrode. is characterized in that a potential difference equal to or higher than a threshold value at which field emission of electrons can occur from the cathode is applied only during a period other than the retrace period of scanning by the electron beam.

[0007]

[Operation] According to the structure of the present invention, electrons are field-emitted from the tip of the cathode due to the potential difference between the control electrode and the control electrode.
An electron beam is formed. Further, by setting the potential difference during the retrace period to a threshold value or less, it is possible to prevent the target from being irradiated with the electron beam during the retrace period.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a conceptual configuration of a vidicon according to an embodiment. As shown in the figure, this vidicon includes a field emission type electron source 1 that is an electron beam source, an accelerating electrode 2 that accelerates the electron beam EB from the electron source 1, and an electron beam E.
A vertical deflection electrode 3 that deflects B in the vertical direction, a horizontal deflection electrode 4 that deflects B in the horizontal direction, and a focusing coil 5 that constitutes an electron lens for focusing the electron beam, forming a uniform deceleration electric field for the electron beam. mesh electrode 99;
It has a photoconductive target 7 formed on the inner surface of the output face plate 6, and is housed in a vacuum container (not shown). Electron source 1
has a silicon substrate 11, and a pyramid-shaped protrusion 12 having a height of, for example, 2 μm is formed in the center thereof to serve as an electron emitting portion, that is, a cathode. Then, on the silicon substrate 11 around the pyramid-shaped protrusion 12, an insulating film 13 made of SiO2, Si3 N4, etc., is slightly thicker than the height of the pyramid-shaped protrusion 12, for example, 3.5 μm thick, and has a similar thickness. is formed, and a control electrode 14 made of an A1 film is provided on its upper surface. And the control electrode 14
is fixed to a support member 15 with a conductive adhesive, and the other end of this support member 15 is fixed to a vacuum container (not shown).

In the above structure, when a voltage of about 100 V is applied to the control electrode 14 with the silicon substrate 11 grounded, electrons are emitted from the tips of the pyramidal protrusions 12 by field emission. The electrons become an electron beam EB, which is accelerated by the accelerating electrode 2, focused by the focusing coil 5, and incident on the photoconductive target 7. At this time, if a deflection voltage is applied to the vertical deflection electrode 3 and the horizontal deflection electrode 4, the electron beam EB is deflected in the horizontal direction (H) and the vertical direction (V), so that the photoconductive target 7
is scanned two-dimensionally by the electron beam EB.

By the way, in scanning the photoconductive target 7, one retrace period (horizontal retrace period) is required for each horizontal scan, and one retrace period is required for each scan of one screen (frame). vertical scanning period is required. In the present invention,
For this reason, the control voltage VC applied to the control electrode 14 is kept below the threshold during the retrace period.

[0011] High-speed ON of the electron beam EB as described above
, OFF becomes particularly effective by using a field emission target like the one of the present invention. That is, JP-A-63-
In devices such as No. 136443 that use liquid metal as an electron emission source, minute protrusions are formed by the balance between the surface tension of the molten metal itself and the electrostatic stress caused by the extraction electrode, so the potential must be lowered during the retrace period. However, with the configuration of the present invention, such inconvenience does not occur at all.

FIG. 2 shows another type of electron source 1 that can be used in the vidicon of the embodiment. In this example, silicon substrate 11 is fixed to support member 15 . Therefore, in this case, a lead wire (not shown) or the like is connected to the silicon substrate 11 and the control electrode 14, and the control voltage VC is connected between them.
It is necessary to apply Note that the accelerating electrode 2 has 2
A bias of approximately 00V may be applied.

FIG. 3 shows yet another type of electron source 1. In this case, the support member 15 is made of an insulating material such as glass, and metal is deposited thereon to form the control electrode 14 and the field emission cathode 120 having projections. Then, the control electrode 14 and the field emission cathode 120
An accelerating electrode 2 is provided thereon with an insulating film 17 interposed therebetween.

FIG. 4 shows an example in which a plurality of pyramidal protrusions 12 are provided on a silicon substrate 11 by microfabrication technology. In the figure (a), one control electrode 14 is provided for a plurality of pyramidal protrusions 12, whereas in the figure (b), a plurality of control electrodes are provided for a plurality of pyramidal protrusions 12. 14 are provided. These cases have the advantage that the amount of electron beam can be increased and that variations in the emission current of individual field emission cathodes can be averaged out.

FIG. 5 shows yet another type of electron source 1. The difference between this electron source 1 and that in FIG. 2 is that the control electrode 14
An adjustment electrode 19 is provided thereon with an insulating film 18 interposed therebetween. By applying an appropriate bias to this adjustment electrode 19, it becomes possible to adjust the angular distribution of the electron beam EB. In the above description, a vidicon was used as an example, but the present invention can also be applied to an SEM (scanning electron microscope).

[0016]

[Effects of the Invention] As explained above in detail, the present invention provides
Due to the potential difference between the cathode and the control electrode, electrons are field-emitted from the tip of the cathode, forming an electron beam. Also,
By setting the potential difference during the retrace period to a threshold value or less, it is possible to prevent the target from being irradiated with the electron beam during the retrace period. Therefore, there is no need to use a heater for heating.
It becomes possible to create an image pickup tube with low dark current, low afterimage, and high resolution.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a vidicon according to an embodiment.

FIG. 2 is a configuration diagram of a first example of a field emission type electron source that can be used in the vidicon of the embodiment.

FIG. 3 is a configuration diagram of a second example of a field emission type electron source that can be used in the vidicon of the embodiment.

FIG. 4 is a configuration diagram of a third example of a field emission type electron source that can be used in the vidicon of the embodiment.

FIG. 5 is a configuration diagram of a fourth example of a field emission type electron source that can be used in the vidicon of the embodiment.

[Explanation of symbols]

1...electron source 11...Silicon substrate 12...Pyramid-shaped process 120...Field emission cathode 13...Insulating film 14...Control electrode 19...Adjustment electrode EB…electron beam 2...Acceleration electrode 3...Vertical deflection electrode 4...Horizontal deflection electrode 5...Focusing coil

Claims (3)

[Claims] 1. An electron beam source that generates an electron beam; an electron optical system that focuses and deflects the electron beam;
In an electron tube device including a target scanned by a deflected electron beam, the electron beam source includes a substrate, a sharp cathode protruding from the substrate,
and a control electrode insulated from the cathode and provided on the substrate, and between the cathode and the control electrode, field emission of electrons from the cathode occurs only during a period other than the retrace period of scanning by the electron beam. 1. An electron tube device characterized in that a potential difference greater than a threshold value that can cause is applied. 2. The electron tube device according to claim 1, wherein the sharp cathode comprises a plurality of cathodes. 3. The electron beam source further includes an adjustment electrode provided on the substrate and insulated from the cathode and control electrode, and a predetermined DC voltage is applied to the adjustment electrode. electron tube device.