JPS61203541A - Electron gun structure for cathode-ray tube - Google Patents

Abstract

PURPOSE:To enable inter-electrode voltage withstand processing without damaging the cathode face by switching G4 electrode at main electron lens section from G2 electrode under manufacture to G1 electrode under usage at the outside of cathode ray tube. CONSTITUTION:The electron gun structure is constructed with beam forming section comprised of cathode 1, G1 electrode 2 and G2 electrode 3 and main lens section comprised of G3 electrode 11, G4 electrode 12, G5 electrode 13 and G6 electrode 14. Then an intermediate potential voltage of 20-40% of that to be applied onto G6 electrode 14 is applied in common onto G3 and G5 electrodes 11, 13. G4 electrode 12 is connected go G2 electrode 2 under manufacturing at the outside of tube while connected to G1 electrode 2 for providing the potential lower than the ground potential under usage. Consequently, main electron lens splitted into two stages will reduce the astigmatism while to improve the resolution and to enable voltage withstand processing without damaging the cathode resulting in improvement of the reliability.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an electron gun assembly for a cathode ray tube.

(Prior Art and its Problems) Conventionally, a pi-potential type electron gun or a uni-potential type electron gun has been used as an electron gun for a cathode ray tube. As shown in FIG. 4, the pi-potential type electron gun has a cathode 1. G1 electrode 2° G2 electrode 3. G3 electrode 4. G
4 electrodes 5 are installed coaxially, G4 electrode 5 is connected to the high voltage power supply,
The s electrode 4 is connected to a medium-high voltage power supply at a potential VF of about 10 to 40% of the high voltage power supply potential Eb! As shown in the equivalent optical model diagram of FIG. After being focused in advance by the main focus lens Lp formed between the G3 electrode 4 and the G311 pole 4, the main focus lens Lhi formed by the G3 electrode 4 and the G4 electrode 5 focuses the light at the minimum on the fluorescent plane P. The beam is focused to have a beam diameter of As shown in Figure 5, the uni-potential type electron gun has a cathode 1. G1 electrode 2. G
2 electrodes 3. G3 [pole 6. G4 electrode7. The G5 electrode 8 is installed coaxially, the G3 electrode 6 and the 051[pole 8 are connected to a common high-voltage power source, and the G4 electrode 7 is connected to a ground potential or a power source close to the ground potential. In this case G3 electrode 6. G4 electrode 7
．． The equivalent optical model shown in FIG. 6 is established in the same manner as described above except that the main focus lens LM is formed by the G5 electrode 8.

Since the pi-potential type electron gun has a large lens strength, the resolution deteriorates significantly due to aberrations especially when the electron beam emitted from the cathode has a high current. However, if the length of the electron gun is constant, the electron optical magnification is small, and the diameter of the focused electron beam becomes sharp at low currents. Even lower potential 02 electrode 3
The G3 electrode 4 facing 10 to 40 of the high voltage power supply potential Eb
%, the potential difference between the G2 electrode 3 and the G3 electrode 4 is small compared to the 03 electrode 6 of a uni-potential electron gun, which is connected to a high voltage power supply, and the withstand voltage characteristics are will be good. On the other hand, in the uni-potential type electron gun, as mentioned above, the 03 electrode 6 is at a high voltage potential, so the G2
1! The potential difference between the pole 3 and the G3 electrode 6 is large, and the withstand voltage characteristics are worse than those of the bifist potential type electron gun. does not diverge as much as a pi-potential type electron gun, reduces the spherical aberration of the main focus lens LM, has less current dependence compared to a pi-potential type electron gun, and can perform focus adjustment with a low voltage. Although it is less affected by high voltage fluctuations, the beam diameter lacks sharpness.

In this way, both the pi-potential type electron gun and the uni-ψ potential type electron gun, which are conventionally used, have their advantages and disadvantages.None of them can obtain a sharp beam diameter in a high current range, and they are difficult to use for high-brightness screens. resolution has deteriorated.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and is an electron gun assembly equipped with a main electron lens that has small aberrations, excellent resolution from low current range to high current range, and good withstand voltage characteristics. The purpose is to provide

(Means for Solving the Problems) The present invention provides an electron beam forming section that includes at least a cathode, a G1 electrode, and a G2 electrode, and a main electron lens section that includes a plurality of main electron lens electrodes on the axis of an electron gun. In the electron gun structure which is arranged coaxially in sequence, the G forming the main electron lens from the cathode side
3 [pole, G4 electrode, G5 electrode, and G6 electrode are arranged coaxially, G3 is the pole and G5 electrode is the final electrode G6t [20~20~ of the anode voltage applied to the pole]
A medium-high focused voltage at G40 is commonly applied, and G4
The electrode is characterized in that it is connected to the G2 electrode outside the cathode ray tube during the cathode ray tube manufacturing process, and to the G1 electrode to which a potential below ground potential is applied when actually used as a cathode ray tube.

(Example) The present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the electron gun assembly according to the present invention includes a cathode 1,
G3 electrodes 11, 04 [poles 12v, G5 electrodes 13, and G6 electrodes 14 are arranged on the axis of the electron gun, respectively. When using a cathode ray tube, the anode voltage Eb is supplied to the G6 electrode 14 from an anode button (not shown), and the G3 electrode 11 and the 05 electrode 13 are connected within the cathode ray tube so that they have the same potential, and the external lead wire of the Kj stem 15 16A is led out of the tube, and when the cathode ray tube is used, a focusing voltage VF at a medium-high potential of about 20 to 40 inches of the high voltage Eb is applied from the external lead-in line 16A.
The pole 12 passes through the internal lead-in wire of the stem 15 and connects to the external lead-in wire 16.
BK is connected. However, during the cathode ray tube manufacturing process, external introduction N16B is connected to external introduction #1 connected to G2 electrode 3.
Externally connected to 6C and connected to G1 electrode 2 when actually used as a cathode ray tube & externally connected to 16D, G1 electrode 2 and G4 [pole 12 are both given a potential EC, which is less than the ground potential. It will be done.

As shown in Figure 2, the equivalent model in this case is that the electron beam emitted from the cathode 1 is diverged from the G1 electrode 2 and G2 to the crossover point O formed near the pole 3, and the electron beam is diverged from the G1 electrode 2 and G2 to the crossover point O formed near the pole 3. Preliminary focusing is performed by a pre-focus lens Lp formed between the 3 and 03 electrodes 11, which is the same as in the conventional electron gun. A concentrated voltage VF at a medium-high potential of the same potential is applied to the G3 electrode 11 and the G51i1:pole 13, and a potential EC1, which is the same potential as the G1 potential and below the ground potential, is applied to the G4 electrode 12 located between them. , a unipotential focusing type electron lens LMI similar to that shown in FIG. 5 is formed. A bipotential fuse type electron lens LM2 is formed between the G5 electrode 13 to which the focusing voltage VF is applied and the G6 electrode 14 to which the anode potential Eb is applied.

Therefore, since the electron beam pre-focused by the main focus lens Lp is focused in two stages on the phosphor screen P by the two main focus lenses so as to have the minimum beam diameter, each main electron lens Lwx, Lux Compared to the single main focus lens LM in the conventional electron gun, the strength of each lens is weaker, and the beam can be gradually focused by the two main electron lenses, so the main lens system Spherical aberration becomes extremely small.

Here, the front stage lens LM is composed of a G3 electrode 11, a G4 pole 12, and a G5 electrode 13, which is a multi-stage focusing system.
The lens action of I and the voltage EC applied to the 04 electrode 12,
The relationship is shown in Figure 3. In the figure, the horizontal axis represents the voltage E C4 applied to the G4 electrode 12 from an independent power source, and the vertical axis represents the voltage E C4 applied to the G4 electrode 12 from an independent power source.
The beam divergence angle α of the lens LMI shown in the figure is shown. As is clear from the figure, when EC4≦O■, α becomes a constant value when α≦2.8 degrees, but when EC4≧200V, α≧3,5
Degree and EC.

α is increasing at a rate of change greater than ≦Ov. Therefore, the smaller the divergence angle α of the front lens LMI, the smaller the spherical aberration can be, so it is necessary to use it with EC4≦O, but ()4' Providing an independent IC source is undesirable because it makes the conditions for using the cathode ray tube uneconomical.

In a normal cathode ray tube, the G2 EC is used at 300V or more, which is inappropriate as a G4 power supply, and the G1 electrode 2 is used at an EC below the ground potential, so the G4 voltage and
It is optimal to use the electrode 12 connected to the 01 electrode 2.

Also, in order to satisfy EC1=EC4≦O, G4 electrode length LG4
is the opening diameter DK of 0.3<LG4/D<0.6
need to be met.

On the other hand, in the manufacturing process of cathode ray tubes, in order to maintain good withstand voltage characteristics between the electrodes of the electron gun structure when the cathode ray tube is used, a high voltage equivalent to several times that during use is applied between the electrodes where there is a high potential difference. , microprotrusions and dirt on the electrode surface are burned out. In the electron gun bridge body of the present invention, first G
6 excluding electrode 14<05 electrode 13 to G3 electrode 11. The G2 electrode 3 to the cathode 1 are set to a common ground potential through the external lead-in wire of the stem 15 outside the cathode ray tube, and a high voltage 2 to 3 times the actual used anode voltage Eb is applied to the G6 electrode 14 from an anode button (not shown). Then, voltage resistance treatment is performed between the G5 and G6 electrodes. Next KG4
1 to G3 opposite pole 12 [pole 11, G5 to pole 13 and G2 to pole 3 and G3 In voltage resistance treatment between electrode 11, stem 1
G3 electrode 11. A high voltage 2 to 4 times higher than the focusing voltage Vr during actual use is applied to the G5 electrode 13, and the G4 electrode 12. G2 electrode 3. G1 electrode 2. The cathodes 1 are connected in common through the external lead-in wire of the stem, set to a ground potential, and subjected to voltage resistance treatment.

On the other hand, the cathode 1 and the G1 electrode 2 face each other at a distance of about 0.3 degrees, and if a discharge current of 500 to 100 OA during the withstand voltage treatment during the cathode ray tube manufacturing process directly flows into the G1 electrode 2. If the cathode 1 exceeds a very small distance and damages the thermionic emission surface of the cathode 1, the cathode current necessary for the cathode ray tube cannot be obtained, and its life becomes extremely short.

However, according to the present invention, during the cathode ray tube manufacturing process, G4 electrode 12 is connected to G2 to pole 3 outside the tube, and G1 electrode 2 is connected to pole 3.
KG3-()4, G4-
The discharge current flowing between the G5 electrodes can be prevented from flowing directly into the G11lt electrode 2, and damage to the thermionic emission surface of the cathode 1 by the discharge current can be effectively avoided. Therefore,
Since the processing voltage can be sufficiently increased without damaging the cathode 1, G2-03, G3-04, C+4
- The withstand voltage quality between the G5 and G5-G6 electrodes can be made sufficiently satisfactory for practical purposes.

Although the above explanation has been about a single electron gun structure having one cathode, it goes without saying that the present invention is also applicable to a multi-beam integrated electron gun structure having a common electrode for multiple cathodes. Nor.

(Effects of the Invention) As described above, according to the present invention, the main electron lens is divided into two stages to make it multi-stage, and the spherical aberration of each stage electron lens can be made extremely small, so that the beam current emitted from the cathode Even if the voltage changes from a low current range to a high current range, the resolution of the image formed on the year plane can be made extremely high. When operating a cathode ray equipped with this electron lens, the 04 electrode is connected to the 01 electrode outside the tube, and an independent power source is not required.
There is no loss in economic efficiency when using cathode ray tubes.

On the other hand, between the G2-G3, G3-G4, and G4-G5 electrodes, 20 to 40% of the anode potential is applied to the G3'tl electrode and the 05 electrode.
Since a moderate to high voltage is applied, there is no electrode that generates a large potential difference as in the conventional uni-potential Φ focus type. Furthermore, during the cathode ray tube manufacturing process, the 04 pole is connected to the G2 pole outside the tube, so voltage resistance treatment between the electrodes can be performed without damaging the cathode surface. The withstand voltage quality can be sufficiently increased. Therefore, it is possible to obtain an electron gun assembly with good withstand voltage characteristics and extremely high reliability.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of the electron gun assembly according to the present invention, Fig. 2 is an optical model thereof, and Fig. 3 shows the relationship between the voltage EC4 applied to the 04 electrode of the front lens and the beam divergence angle. The graphs, FIGS. 4 and 5, are equivalent element theory diagrams of the conventionally used Biken potential-four, respectively. 1...Cathode, 2...Glt pole, 3...
...G2 electrode, 11...G3 electrode, 12.
...G4'! ! pole, 13...G5 electrode,
14... G6 as pole, 15... Stem,
16A to 16D... External lead-in line, Lp...
・・Pre-focus lens, LM, LMI, LM2
−・・・・Tsuzu bell IJLIJ Figure 3

Claims (1)

[Claims] In a cathode ray tube electron gun assembly in which an electron beam forming section consisting of at least a cathode, a G1 electrode, and a G2 electrode and a main electron lens section consisting of a plurality of main electron lens electrodes are sequentially arranged coaxially on the axis of the electron gun, G3 forming the main electron lens from the cathode side
Four electrodes consisting of the electrode G4 electrode, G5 electrode, and G6 electrode are arranged coaxially, and a focusing voltage of 20 to 40% of the anode voltage applied to the G6 electrode, which is the final electrode, is applied to the G3 electrode and the G5 electrode. A switching means is provided which connects the G4 electrode to the G2 electrode outside the cathode ray tube during the cathode ray tube manufacturing process, and connects it to the G1 electrode to which a potential below ground potential is applied when actually used as a cathode ray tube. An electron gun assembly for a cathode ray tube characterized by the following.