JPH0215245Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an electron gun suitable for application to a high-resolution cathode ray tube.

BACKGROUND ART AND THEIR PROBLEMS For example, a high-resolution cathode ray tube in which the horizontal frequency is twice the normal frequency is required to have wideband frequency characteristics. To achieve this, it is necessary to improve the reactance component of the cathode of this cathode ray tube in addition to the video amplifier that drives this cathode ray tube.

Figures 1 and 2 show a cathode electrode K and a first grid electrode of an electron gun in a conventional cathode ray tube.
Part _G1 is shown. In these figures 1
is a cathode ceramic disk, and a circular hole 2 is formed in the center of this disk 1. Further, 3 is a cylindrical cathode sleeve, 4 is a cathode cap covering the tip thereof, and these constitute a cathode electrode K. This cathode sleeve 3 is disposed so as to pass through the circular hole 2 of the disk 1. Further, cathode pins 5a and 5b are installed on the short diameter side of the disk 1, and V-shaped tabs 6a and 6 are provided between the cathode pins 5a and 5b and the cathode sleeve 3, respectively.
b are arranged and welded to each other, and the cathode sleeve 3
is fixed. Further, rest pins 7a ₁ , 7a ₂ , 7a ₁ and 7a ₂ are installed on the disk 1, a heater rest 8a is fixed to the rest pins 7a ₁ and 7a ₂ , and rest pins 7b 1 and 7b 2 are fixed to the rest pins 7a ₁ and 7a ₂ . A heater rest 8b is fixed to.

Further, inside the cathode sleeve 3, for example, a double helical type heater 9 is disposed, and both ends thereof are connected to heater rests 8a and 8b, respectively. Further, _G1 is a first grid electrode, 10 is a spacer, and 11 is a retainer.

Further, although not shown, a predetermined voltage is applied to the heater 9 via heater rests 8a and 8b, and cathode pins 5a and 5a are applied to the cathode sleeve 3, respectively.
A drive signal is applied via V-shaped tabs 5b and 6a, 6b.

In such a conventional example, the cathode electrode K
and other electrodes, such as heater 9, heater rest 8
The capacitance between a, 8b, electrode _G1 , etc. is large,
In this state, wideband frequency characteristics cannot be obtained.

Purpose of the invention The present invention has been made in view of these points, and is intended to reduce the capacitance between the cathode electrode and other electrodes, thereby making it possible to obtain broadband frequency characteristics.

Summary of the Invention In order to achieve the above object, the present invention is such that a heater rest is fixed to the outer surface of the first grid electrode via an insulator.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

In the figure, 12 is a cathode ceramic disk. The thickness of this disk 12 is smaller than that in the embodiment described above. For example, what was 2 mm in the conventional example is now about 1 mm to 0.5 mm. Further, the disk 1 in the conventional example was made of, for example, alumina, but the disk 12 of the present example uses, for example, steatite, which has a lower dielectric constant.

Further, an elongated hole 13 is formed in the center of the disk 12 and extends in the short diameter direction. Further, a round hole 14 is formed around the elongated hole 13.

Further, 15 is a cylindrical cathode sleeve constituting the cathode electrode K, and this cathode sleeve 15 is disposed so as to pass through the center of the elongated hole 13 described above. Although not shown, the tip of the cathode sleeve 15 is coated with an electron radioactive substance such as BaO. The diameter of this cathode sleeve 15 is smaller than that in the conventional example. For example, in the conventional example, the diameter
What used to be 1.5mm is now around 0.7mm.

Further, one cathode pin 16 is installed close to the elongated hole 13 on the long diameter side of the disk 12 . And this cathode pin 16 and cathode sleeve 1
V-shaped tabs 17 are disposed and welded between the cathode sleeve 15 and the disk 12, thereby fixing the cathode sleeve 15 to the disk 12.

Furthermore, a heater 18 whose periphery is covered with an insulating material is disposed inside the cathode sleeve 15. In this example, the heater 18 is shaped like an inverted U. Both ends of this heater 18 are welded and electrically connected to one end of plate-shaped heater rests 19a and 19b.

Further, G ₁ is a first grid electrode arranged to cover the disk 12. On the outer surface of this electrode _G1 , metal pins 20a and 20b for fixing the heater rest are attached to an insulating material, such as a ceramic insulator 21.
Fixed via. That is, the metal pins 20a and 20b are planted in a ceramic insulator 21, and a metal terminal 22, one end of which is fixed to the ceramic insulator 21, is welded to the electrode _G1 . This metal pin 20
The other ends of the heater rests 19a and 19b described above are welded to a and 20b, respectively, and the heater rests 19a and 19b are fixed.

Further, one ends of heater leads 23a and 23b are welded and electrically connected to the other ends of heater rests 19a and 19b, respectively, and the other ends of heater leads 23a and 23b are welded to stem pins 24 and 25, respectively. connected electrically. Then, the stem pins 24 and 25, the heater leads 23a and 23b, and the heater rest 19
A predetermined voltage is applied to the heater 18 via a and 19b.

In addition, the cathode pin 6 has a cathode lead 26.
One end of the cathode lead 26 is welded to be electrically connected, and the other end of the cathode lead 26 is welded to a stem pin 27 for electrical connection. Then, the stem pin 27, cathode lead 26, cathode pin 1
6. A drive signal is applied to the cathode sleeve 15 via the V-shaped tab 17. In this case, the stem pin 27 is placed as far away from other stem pins as possible and at the shortest possible distance, so that a large capacitance does not occur.

Further, 28 is a metal member for supporting the electrode _G1 and the like. This metal member 28 is welded and fixed to a mounting portion 29 formed on the electrode _G1 . Also,
A predetermined voltage is applied to the electrode G ₁ via this metal member 28 . Although not shown, several metal members similar to this metal member 28 are separately provided for supporting purposes only.

Further, although not shown in the drawings, spacers and retainers are arranged on one surface and the other surface of the disk 12 as in the conventional example.

This example is constructed as described above, and since the heater rests 19a and 19b are fixed to the outer surface of the electrode _G1 via the ceramic insulator 21, the distance from, for example, the cathode electrode K is longer, and the disk Compared to the case where a rest pin is planted on the top and fixed, the cathode electrode K and the heater rest 19a,
19b, the capacitance becomes significantly smaller.

In addition, the thickness of the disk 12 is reduced, a round hole 14 is formed in the disk 12, the disk 12 is made of a material with a low dielectric constant, and there is only one cathode pin 16 on the long axis side of the disk 12 ( For example, as the dielectric constant between the cathode electrode K and the electrode _{G 1 decreases} , the distance between them increases, and the static between the cathode electrode K and the electrode G ₁ increases. Capacity becomes significantly smaller.

Furthermore, since the heater 18 has an inverted U-shape, for example, the area facing the cathode electrode K is reduced, and the capacitance between the cathode electrode K and the heater 18 is reduced.

Furthermore, since the diameter of the cathode sleeve 15 is reduced, for example, the opposing area between the cathode electrode K and other electrodes is reduced, and the capacitance between the cathode electrodes K and other electrodes is reduced.

As described above, according to this example, the capacitance between the cathode electrode K and other electrodes, such as the heater rests 19a and 19b, the heater 18, and the electrode _G1 , is significantly smaller than in the conventional example. For example, the capacitance, which was about 6 pF in the conventional example, is about 1 pF in this example. Accordingly, according to this example, for example
It is possible to obtain wideband frequency characteristics of 150MHz.

Effects of the invention According to the invention described above, since the heater rest is fixed to the outer surface of the first grid electrode via an insulator, the result is the same as if the rest pin was removed, and the rest pin is attached to the disk as in the conventional example. The capacitance between the cathode electrode and the heater rest is significantly smaller than when the heater rest is planted and fixed. Therefore, broadband characteristics can be obtained, and it is suitable for application to, for example, high-resolution cathode ray tubes.

[Brief explanation of the drawing]

FIGS. 1 and 2 are a cross-sectional view and a plan view of the main parts showing a conventional example, respectively, and FIG. 3 is a perspective view of the main parts showing an embodiment of the present invention. 12 is a cathode ceramic disk, 15 is a cathode sleeve, 16 is a cathode pin, 17 is a V
letter-shaped tabs, 18 are heaters, 19a and 19
20a and 20b are metal pins for fixing, 21 is a ceramic insulator, and 22 is a metal terminal.

Claims (1)

[Scope of utility model registration request] 1. An electron gun of cathode drive type, characterized in that a heater rest is fixed to the outer surface of a first grid electrode via an insulator.