JPS581956Y2 - electron gun - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to improvements in electron guns such as picture tubes and image pickup tubes, and aims to reduce power loss in electron guns having beam-limiting apertures.

First, FIG. 1 shows the overall structure of a conventional electron gun for an image pickup tube.

This image pickup tube is an electrostatic focusing electron gun, and 1 is an electron emitting section having a cathode electrode that emits thermoelectrons and an anode electrode that applies a voltage that accelerates the electrons.

Reference numeral 2 denotes a focusing section that electrostatically focuses the electron beam emitted from the electron emitting section 1 and forms an image on a target section (not shown), and the electrodes 3, 4, and 5 constitute a unipotential focus lens. .

The electron emitting unit 1 normally has a cathode electrode, an anode electrode, and a grid electrode for controlling the beam current, but in the case of an image pickup tube, since there is no need to control the beam current, the grid electrode can be omitted.

The structure of the electron emitting section in that case is shown in FIG.

6 is a cathode K, 7 is a cathode flat plate electrode Kp, 8 is an anode electrode AP, and a beam limiting aperture 9 is provided on the anode electrode.

In the image pickup tube, this aperture is used as a light source, and its image is focused onto the target by a lens in the focusing section.

Usually, the diameter of this aperture is about 20 to 40 μφ, and the maximum transmission current is about 1 to 2 μA.

Make the potential of KP the same as that of the cathode, and set the potential of AP to v
A, by appropriately selecting the distance d between KP and AP, a current density similar to that of the three-electrode method can be obtained using an aperture of 9.
You can get it above.

In this case, the problem is that the electron beam emitted from the cathode has a small diameter through the aperture 9, so most of it collides with the anode electrode, and the kinetic energy of the electron beam is converted into thermal energy.

That is, if the cathode current is set, the anode current is set, the transmission current is IAT, and the anode voltage is vA, the power loss PA when pressing the anode is IA"IK IAT27, so PA2IA-VAAlx-vA IK = 3mA , when Va=300V, p, medium 0.9W
This is a fairly large power loss when considering a portable television camera.

The present invention provides an electron gun that eliminates these drawbacks and reduces the power loss applied to the anode electrode having a beam-limiting aperture. The structure of the electron emitting section is shown in FIG. 3 below.

In the figure, 11 is a cathode, 112 is a cathode flat plate electrode KP, 13 is an anode electrode AP, and 14 is an intermediate electrode MP provided between the cathode flat plate electrode 12 and the anode electrode 13.

A beam limiting aperture 15 is provided on the anode electrode 13, and an aperture 16 having a diameter smaller than the cathode diameter but larger than the diameter of the aperture 15 is provided on the intermediate electrode 14.

If the distance between K and MP is dl, and the distance between MP and AP is d, then the M electrode voltage vM is 2P, and an aperture lens is not formed.

Since the present invention is constructed in this way, the aperture is 15.
The above current density is equal to the current density without the MP electrode by X, and most of the cathode current is blocked by the MP electrode, so the power loss at the AP electrode is significantly reduced.
Moreover, the power loss at the MP electrode also becomes a sufficiently small value because vM becomes sufficiently small by making dl small.

For example, d1+d2-=2mm, d1''0.
When the aperture diameter of 15 is 30μ and the aperture diameter of 16 is 100μ when 2 mrn, vA-300v, IK
=3mA, Transmission current of 16 IMT=20μA115
The transmission current of AT is -2μA, so vM = 30v from 1
becomes.

Therefore, the power consumption PM at the MP electrode is PM = IM - VM2 IK - VM = 0.09 The power consumption PA at the WAP electrode is pA = I, -v, = iMTVA = 0.006W, that is, the total power consumption is approximately 0. At 1W, the power can be reduced to about 1/9 of the conventional power.

In the explanation of one embodiment of the present invention, an electron gun for an image pickup tube was taken up, but it goes without saying that the present invention can also be applied to an electron gun for a picture tube that uses an anode aperture as a light source.

In that case, the video signal is sent to the MP electrode or cathode electrode,
Added to KP.

As described above, the present invention has a cathode electrode, a cathode flat plate electrode parallel to the cathode surface, and an anode electrode having a surface parallel to the cathode flat plate electrode and an aperture that limits the beam diameter. An intermediate electrode having an aperture smaller than the cathode diameter and larger than the aperture diameter of the anode electrode is provided in parallel with the cathode flat plate electrode, and the distance between the intermediate electrode and the cathode flat plate electrode is d□, and the anode electrode is When the distance between is d2, the cathode plate electrode voltage is O volts equal to the cathode electrode voltage, and the anode electrode voltage is vA, the intermediate electrode voltage is vM, and it has a beam limiting hole,
Furthermore, since the intermediate electrode does not constitute an aperture lens, no inconvenience will occur.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional image pickup tube, Fig. 2 is a sectional view of the electron emitting part of a conventional electron gun, and Fig. 3 shows the configuration of the emitting part of an electron gun according to an embodiment of the present invention. FIG. 11... Cathode, 12... Cathode flat plate electrode, 13... Anode electrode, 14...
...Intermediate electrode, 16...Aperture.

Claims (1)

[Claims for Utility Model Registration] A cathode electrode, a cathode flat plate electrode parallel to the cathode electrode, and an anode electrode having a surface parallel to the cathode flat plate electrode and an aperture that limits the beam diameter; An intermediate electrode having an aperture smaller than the cathode diameter and larger than the aperture diameter of the anode electrode is provided between the anode electrode and the cathode plate electrode, and
When the distance between the intermediate electrode and the cathode plate electrode is dl, the distance from the anode electrode is d2, the cathode plate electrode voltage is O volts equal to the cathode electrode voltage, and the anode electrode voltage is VA, the intermediate electrode voltage vM is An electron gun characterized by the following.