JPS6035957Y2 - cathode ray tube - Google Patents

Description

[Detailed description of the invention] This invention is used in cathode ray tube control circuits, etc. by suppressing the large current flowing during high voltage discharge by increasing the electrical resistance of the internal conductive coating provided on the inner surface of the vacuum envelope. This invention relates to a cathode ray tube that has been improved to prevent damage to semiconductor components.

FIG. 1 shows a schematic structure of a conventional cathode ray tube used in a television receiver.

As shown in the drawings, an inner conductive film 3 is coated on the inner surface of a funnel portion 2 constituting the vacuum envelope of the cathode ray tube 1, and an outer conductive film 4 is coated on the outer surface.

Furthermore, electrodes of an anode section 6 and a cathode section 7 constituting an electron gun are inserted into the neck section 5 of the cathode ray tube 1.

The cathode section 7 is connected to a chassis circuit section 10 of the television receiver through a stem end 8 and a socket 9.

On the other hand, a high voltage is applied to the anode button 11 embedded in the center of the funnel section 2 from the flyback transformer 12 of the television receiver, and this voltage is applied to the anode section 6 through the internal conductive coating 3.

A deflection yoke 13 attached to the outer walls of the funnel part 2 and the neck part 5 is connected to the chassis circuit part 10 by a lead wire 14, and the external conductive coating 4 and the ground terminal of the socket 9 are connected by a lead wire 15.

Further, an antenna getter 20 is attached to the tip of the anode section 6, and a getter 21 welded to the end of the getter spring 22 is positioned near the center of the funnel section 2.

In the cathode ray tube 1 having such a configuration, the anode portion 6
When a high voltage discharge occurs between the cathode portion 7 and the cathode section 7, most of the charge contributing to this high voltage discharge is transferred to the inner conductive coating 3 and the outer conductive coating 4 of the cathode ray tube 1, or between the inner conductive coating 3 and the deflection yoke 13. This electric charge flows from the inner conductive film 3 to the outer conductive film 4 through the anode section 6 and the cathode section 7 because it is stored in the capacitance existing therebetween.

At this time, since the capacitance is, for example, 2000 pF, the electric energy stored therein is quite large, and since the high-pressure discharge time is short, for example, about 100 n3, the flowing current reaches several hundred A.

Therefore, due to electromagnetic induction or electrostatic induction caused by this discharge current, an abnormal voltage is applied to the semiconductor elements used in the chassis circuit section 10 of the television receiver, and these elements are destroyed.

Furthermore, when a cathode ray tube is used in a computer or the like, it may cause malfunction.

Therefore, in order to eliminate such accidents, there is a method of limiting the discharge current during high voltage discharge by forming the internal conductive coating 3 through which the discharge current flows as described above with a high-resistance conductive coating having a large electrical resistance value. However, since the internal conductive coating 3 of the neck portion 5 is short-circuited by the antenna getter 20, the charge accumulated between the internal conductive coating 3 and the deflection yoke 13 is It was difficult to limit the current.

On the other hand, the antenna getter 2 attached to the anode part 6 of the electron gun
It has been considered to attach a getter to the anode button 11 instead of 0, or to attach a getter to the mask 17 facing the fluorescent surface of the panel section 16 of the cathode ray tube 1. Because it is difficult to attach the getter, it is necessary to attach the getter before sealing the panel section 16 and funnel section 2 of the cathode ray tube 1. In that case, the getter will pass through air at a temperature of 450 to 500 degrees Celsius.
There is a risk that the getter will oxidize and the life span of the cathode ray tube will no longer be guaranteed.

This idea was made in view of the above points, and by increasing the resistance value of the internal conductive coating and attaching the antenna getter to a mounting piece embedded in the bead glass, short circuits of the internal conductive coating due to the getter spring can be prevented. It is an object of the present invention to provide a cathode ray tube that can effectively limit the discharge current during high voltage discharge.

This invention will be explained in detail below based on illustrated embodiments.

FIGS. 2 to 4 show an embodiment of this invention, in which a high-resistance internal conductive coating 3A is used, and the antenna getter 20 is attached to a mounting piece 24 embedded in a bead glass 23. The only difference is that the other configurations are the same as those shown in FIG.

As shown in FIG. 3, the mounting piece 24 has a shape in which two strip plates are arranged in parallel and the side surfaces of one end of the plates are bridged.The getter spring 22 is welded to the bridged part, and the other end is connected to the getter spring 22. part is embedded in the bead glass 23.

Bead glass 23 is supported by shield cup 25.

As shown in FIG. 4, this shield cup 25 is formed to hold the bead glass 23 without touching the mounting piece 24, and thereby prevents the high voltage applied to the anode portion 6 when an intraluminal discharge occurs. Dielectric strength sufficient to withstand voltage is ensured.

The cathode ray tube according to this invention is constructed as described above, and the antenna getter 20 and the anode section 6 are arranged on the glass bead 2.
3, the discharge current during discharge flows through the high-resistance internal conductive coating 3A, thereby limiting the discharge current.

That is, since one end of the antenna getter is installed so as to be insulated from the internal conductive coating, it is possible to eliminate short circuits of the internal conductive coating caused by the antenna getter, suppress the large current flowing during high voltage discharge, and Destruction of semiconductor components used in control circuits and the like can be prevented.

Further, since the getter is attached to the electron gun via the getter spring, the getter can be easily inserted into the funnel.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the schematic structure of a conventional cathode ray tube;
3 is a perspective view of a mounting piece supporting a getter spring, and FIG. 4 is a perspective view of a shield cup. 1...Cathode ray tube, 2...Funnel part, 3A...High resistance internal conductive coating, 4...
...Outer conductive coating, 5...Neck part, 6...
... Anode part, 20 ... Antenna getter, 2
1...Getter, 22...Getter spring, 23...Glass bead, 24...
...Mounting piece, 25...Shield cup. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] In a cathode ray tube in which an internal conductive coating is applied to the inner surface of a vacuum envelope, and an antenna getter is installed adjacent to the antenna getter, the getter spring is attached to one end of the getter spring. A cathode ray tube, characterized in that it is attached to an electrode at the tip via a mounting piece embedded in a glass bead, and the antenna getter is insulated from the electrode.