JPS6116596Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a cathode ray tube, and more particularly to a cathode ray tube having improved withstand voltage characteristics.

In the conventional cathode ray tube shown in FIG.
It is blocked by. A heater 3, a cathode 4, a first lattice 5, a second lattice 6, a third lattice 7, and an anode 8 are arranged in this neck part 1 in the axial direction from the stem 2 side, and they are arranged in a predetermined manner by a bead glass 9. is maintained at an interval of Further, a convergence cap 10 is welded to the anode 8 and connected to an internal conductive film 12 by a spacer 11. Also, the second grid 6
Alternatively, the third lattice 7 has inner leads 13a, 1
3b to the stem bins 14a, 14b.

In the operating state of the cathode ray tube, the anode 8 has approximately
A voltage of 24 KV, about 4 KV is applied to the third grid 7, about 600 V to the second grid 6, and about -100 V to the first grid 5.

Now, when conductive particles such as the internal conductive film 12 adhere to the surface of the third lattice 7 facing the anode 8, electric field concentration occurs at the tips of the particles and unnecessary electrons are generated. This is called a first unnecessary electron source 15. Most of the unnecessary electrons from the first unnecessary electron source 15 reach the anode 8, but some of them reach the inner wall of the neck near the anode 8, where they emit secondary electrons and gradually become positive. Charge. If the inner wall of the network portion is positively charged, more electrons flow in, the vicinity thereof is also positively charged, and the charged portion finally moves to the vicinity of the first unnecessary electron source 15.

Then, if the potential of the charged part becomes high enough to exceed the dielectric breakdown voltage between it and the electrode near the first unnecessary electron source 15, a discharge will occur between the two.
When it does not exceed the voltage, no discharge occurs and the potential settles to a constant value. At this time, if there is a protrusion such as a burr on the electrode of the cathode 4, unnecessary electrons are generated due to the electric field from the electric charge charged on the inner wall of the neck near the first unnecessary electron source 15. This is called a second unnecessary electron source 16.

The unnecessary electrons from this second unnecessary electron source 16 are
It flows into the positively charged part of the inner wall of the above neck part,
The inner wall of the neck portion in the vicinity is also positively charged, and the electron beam gradually moves and stops near the second unnecessary electron source 16. Furthermore, the potential at that position becomes higher and eventually creeping discharge occurs between the cathode 4 and the anode 8 via the inner wall of the neck portion, damaging the cathode 4 and the heater 3.

This idea was made in view of the above drawbacks, and in order to prevent creeping discharge, a space where the bead glass and the inner wall of the neck directly face the third lattice inner lead, one end of which is connected to the third lattice electrode. The present invention provides an electron gun provided with conductive leads arranged without contacting the inner wall of a neck portion.

This invention will be explained below with reference to FIGS. 2 and 3.

The same reference numerals as in FIG. 1 indicate the same or corresponding parts.
In FIG. 2 and FIG. 3, the bead is placed in a limited area near the bead glass 9, that is, in the area within the inner periphery of the neck part 1 where the electrodes such as the cathode and the first grid do not directly face the inner wall of the neck part 1. The third grating 7 in FIG. The conductive leads 17a, 17b are connected to the inner lead 13b or the inner lead 13a of the second lattice 6.
are arranged so as not to come into contact with the inner wall of the neck portion 1. At this time, the conductive leads 17a and 17b extend across the bead glass 9 from one outer side of the bead glass 9 to the opposite side.

4 and 5 show conductive leads 17a, 1.
An example of the shape of 7b is shown.

In FIG. 2, when electrons from the first unnecessary electron source 15 move a positively charged part to the inner wall of the neck part facing the electrons, the lines of electric force from the charge are transferred by the conductive lead 17a of this invention. The positively charged portion does not move to the vicinity of the cathode 4 because it is blocked and cannot enter the second unnecessary electron source 16, and therefore the electrons from the second unnecessary electron source 16 do not flow. Therefore, creeping discharge to the cathode 4 and heater 3 can be prevented.

Also, suppose that the lines of electric force from the inner wall of the network part 1 near the first unnecessary electron source 15 are connected to the second unnecessary electron source 1.
6 and the positively charged portion moves toward the cathode 4, since the conductive lead 17b is near the path, the charged charge will be discharged to the conductive lead portion 17b, causing the cathode 4 and the heater Creeping discharge to No. 3 will no longer occur. Therefore, the cathode 4 and heater 3 will not be damaged.

Furthermore, since the conductive leads 17a and 17b are arranged so as not to come into contact with the inner wall of the neck portion 1 and only in a limited area near the bead glass 9, it is assumed that the leads 17a and 17b are deformed. Even if this occurs, there is no risk of contacting the first grid 5 or the second grid 6 and causing a short circuit accident.

Since the conductive leads 17 are formed by the inner leads 13a of the second lattice 6 or the inner leads 13b of the third lattice 7, the number of parts for assembly is small and workability is improved, which is rational.

In the embodiments shown in FIGS. 2 and 3, one of the two bead glasses is connected to the inner lead 13 of the third grid 7.
b to form the conductive lead 17b, and the other to the inner lead 13a of the second lattice 6 to form the conductive lead portion 1.
7a, it goes without saying that a specially designed conductive lead may be provided on the other of the two bead glasses.

As explained above, this invention has a third grid inner lead whose one end is connected to the third grid electrode.
Since the conductive lead part is placed in the space where the bead glass and the inner wall of the neck directly face each other and is placed without contacting the inner wall, neck glass cracks do not occur during the manufacturing process, making it practical. Furthermore, since the positively charged part does not move to the inner wall of the neck part 1 near the cathode 4, the heater 3, or the stem 2 part, where there are many cold emission sources, the condensation effect is enhanced. , the withstand voltage characteristics can be dramatically improved, and the assemblability and workability are also good.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a conventional electron gun, FIG. 2 is a vertical cross-sectional view of an electron gun showing an embodiment of this invention, and FIG.
This figure is a side view of FIG. 2, and FIGS. 4 and 5 are perspective views showing examples of inner leads of the second lattice and third lattice in which conductive lead portions are formed, respectively. In the figure, 1 is a neck part, 4 is a cathode, 5 is a first lattice, 6 is a second lattice, 7 is a third lattice, 8 is an anode, 9 is a bead glass, 13a, 13b are inner leads, 17a, 17b are This is a conductive lead part.

Claims (1)

[Scope of utility model registration request] At least a first lattice, a second lattice, and a third lattice are housed between a cathode and an anode in a network made of an insulating material, one end of which is connected to the third lattice electrode, and a high voltage is applied to the anode. and a third grid inner lead for applying a voltage to the third grid electrode that is lower than the low voltage applied to the second grid electrode, and facing the third grid electrode and connected to the network. Creeping discharge generated along the surface of the bead glass between the cathode and the anode, which is disposed in a space where the inner wall of the part and the bead glass holding the third grid electrode directly face each other without contacting the inner wall of the neck part. The third conductive lead above
A cathode ray tube characterized by being used also as a lattice inner lead.