JPS5814509Y2 - Indirectly heated cathode - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to structural improvement of cathode ray tubes used in electron tubes such as cathode ray tubes.

In general, the cathode structures of cathode ray tubes are classified based on their heating method into two types: direct heating type and indirect heating type.

In the former direct heating type, an electron emitting substance is coated on a heater and is directly heated to emit thermionic electrons.

In the latter indirect heating type, an electron emitting substance is coated on a cathode cylindrical body housing a heater, and this is indirectly heated by a heater.

In any case, the cathode section of the cathode ray tube is fixed at a fixed position within a bottomed cylindrical control electrode (first grid), and thermionic electrons from the electron radioactive material are emitted from the control electrode as a beam. The configuration is normal.

Now, a conventional example of the above-mentioned indirectly heated cathode is shown in FIG. 1. 1 is a cathode cylinder, 2 is a cap fixed to the upper end of the cathode cylinder 1, and 3 is an electron cap attached to the top surface of the cap 2. Radioactive material,
4 is a heater inserted into the cathode cylindrical body 1.

Further, 5 is a bottomed cylindrical control electrode, 6 is an insulating support for storing and fixing the cathode cylindrical body 1 within the control electrode 5, and 7 is a spacer.

The spacer 7 is formed of a metal plate that is easy to process, and is inserted between the control electrode 5 and the insulating support 6.
Regulate the position of.

That is, the spacer 7 is first inserted into the control electrode 5, and then the insulating support 6 to which the cathode cylindrical body 1 is fixed in advance is inserted into the control electrode 5, and the insulating support 6 is inserted at the position where the spacer 7 stops. By fixing the periphery to the inner surface of the side wall of the control electrode 5, the cathode cylindrical body 1 is automatically accommodated and fixed at a fixed position within the control electrode 5.

By the way, in the above conventional structure, when the heater 4 is energized to heat the electron emitting material 3, the emitted thermoelectrons are focused and emitted from the beam hole 8 provided at the center of the upper surface of the control electrode 5.

At this time, the control electrode 5 is also heated by conduction heat and radiant heat, but if it is heated too much, thermoelectrons are also emitted from there, causing a so-called grid emission phenomenon.
This may make the operating characteristics of the electron tube unstable.

Furthermore, if the positional and dimensional relationship between the control electrode 5 and the cathode cylindrical body 1 deviates, variations in cutoff characteristics will occur.

Therefore, conventionally, the positions of the control electrode 5 and the cathode cylindrical body 1 have been regulated by interposing the spacer 7 and the insulating support 6.

However, in the combination of the spacer T and the insulating support 6, dimensional errors inevitably occur, resulting in variations in cutoff characteristics.

Furthermore, the metal spacer 7 has the effect of promoting heating of the control electrode 5, making it difficult to prevent the grid emission phenomenon.

The present invention solves the above conventional problems and provides an indirectly heated cathode ray tube without a spacer.

Hereinafter, the present invention will be explained with reference to the drawings.

In FIGS. 2 and 3, parts with the same reference numerals as those in FIG. 1 have the same structure as the conventional one.
to the configuration point.

That is, the cathode cylindrical body 1 is fitted and fixed at the center of the insulating support 9, and a protrusion 10 is provided in the basic configuration to be fitted into the control electrode 5 in the following manner.

Further, a pole 11 for temporarily fixing the heater is attached to this insulating support 9.

The protrusion 10 is a substitute for a conventional spacer, and is formed to protrude uniformly and integrally from the periphery of the insulating support 9, and by bringing its tip into contact with the back surface of the control electrode 5. , the control electrode 5 and the cathode cylindrical body 1 are positioned.

Note that the protrusions 10 do not necessarily need to be provided over the entire periphery of the insulating support 9, and a plurality of protrusions 10 may be arranged at equal intervals.

Further, in addition to the configuration in which the protrusion 10 is provided along the side surface of the insulating support 9 and adhered to the inner surface of the side wall of the control electrode 5, it is also possible to form the protrusion 10 in a protruding position away from the side surface of the insulating support 9, for example. It is.

Next, the above-mentioned pole 11 will be explained.

This pole 11 is attached to the lower part of the insulating support 9, and the heater 4 is temporarily fixed at a midway point.

This is for the purpose of ensuring insertion of the heater 4 into the cathode cylindrical body 1, and is used as follows.

In other words, as shown in Figure 4, when assembling the cathode, first,
The cathode cylindrical body 1 is fitted into the insulating support 9, and with the opening of the cathode cylindrical body 1 facing upward, the heater 4 is inserted and temporarily fixed to the pole 1.

At this time, the work is difficult unless the heater 4 is temporarily fixed.

In fact, in the past, the gruesome cylindrical body 1 was placed sideways and the heater 4
This is because unless the heater 4 is inserted, work efficiency is poor, and it is not always possible to insert the heater 4 completely to the back.

After that, the control electrode 5 may be fitted onto the insulating support 9.

As explained above, according to the present invention, the position of the control electrode can be regulated by the protrusion that is integrated with the insulating support, and therefore,
It is possible to significantly reduce dimensional errors during assembly,
Variations in cutoff characteristics can be prevented.

Furthermore, since no special spacer is required, the number of parts can be reduced and assembly work efficiency can be improved.

Furthermore, since no spacer is required, the heating of the control electrode is reduced, thereby reducing the grid emission phenomenon and stabilizing the characteristics.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part of a conventional indirectly heated cathode ray tube, FIG. 2 is a cross-sectional view of a main part showing an embodiment of a cathode ray tube according to the present invention, and FIG.
The figure is a cross-sectional view taken along the line A--A in FIG. 2, and FIG. 4 is an explanatory exploded view of FIG. 2. 1... Cathode cylindrical body, 4... Heater,
5... Control electrode, 9... Insulating support,
10...Protrusion.

Claims (1)

[Scope of utility model registration request] A cylindrical cathode containing a heater is fitted into a cylindrical control electrode with a bottom through an insulating support, the insulating support having an integral protrusion that comes into contact with the back surface of the control electrode. An indirectly heated cathode characterized by comprising: