JPH0479461B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an electron gun for a cathode ray tube, and in particular to an electron gun for use in a cathode ray tube to prevent malfunctions and destruction of electrical circuits and peripheral equipment for operating the cathode ray tube due to internal discharge of the tube. The present invention relates to an electron gun for cathode ray tubes having a structure to obtain.

[Technical background of the invention and its problems]

Cathode ray tube electron guns, which are used to provide information to computer terminals, generally have a high voltage electrode to which a relatively high voltage is applied to accelerate the cathode rays, and a relatively high voltage electrode to focus or modulate the cathode rays. It consists of low voltage electrodes to which low voltage is applied.

The voltage difference between these high voltage electrodes and low voltage electrodes depends on the type of cathode ray tube, but even if it is low,
8kV, the highest one is about 30kV, and the distance between the high voltage electrode and the low voltage electrode adjacent to this electrode is the same as the voltage difference normally used to prevent discharge from occurring due to the voltage difference between the two. starting voltage
The interval is set to approximately 1.5 times to 2 times. An electron gun with such a structure is housed inside a high-vacuum cathode ray tube.

However, as mentioned above, even if a sufficient distance is provided between the high-voltage electrode and the low-voltage electrode compared to the voltage difference normally used, trace amounts of impurities (such as dust) and ions may remain inside the cathode ray tube. often gets between the high-voltage electrode and the low-voltage electrode, causing a discharge between the high-voltage electrode and the low-voltage electrode.

As a result of this discharge, the low-voltage electrode momentarily becomes almost equal to the voltage of the high-voltage electrode, which adversely affects the power supply circuit for operating the cathode ray tube, the video amplifier, and other electrical circuits and peripheral equipment, causing them to malfunction. In the worst case scenario, this can lead to phenomena such as destruction.

Conventionally, in order to reduce the negative effects of in-tube discharge development on electrical circuits and peripheral devices connected to low-voltage electrodes, one side of the spark gap was attached to the electrode lead wire of each electrode outside the cathode ray tube, and the other side was as shown in Figure 1, a conductive type with a protrusion 3 around the external lead terminal 1 of each electrode outside the cathode ray tube to obtain an appropriate discharge starting voltage for each electrode. A grounding part 2 made of a plate or a wire is provided, and this grounding part 2 is grounded 8.

FIG _. 2 shows _how the discharge current flows in the structure of FIG _. Taking as an example a unipotential type battery consisting of a third grid ₅₁ and a fifth grid ₅₂ which are voltage electrodes, the flow of discharge current is shown by a broken line 4.

As represented in Figure 1, all _conventional discharge countermeasures are installed by forming a predetermined discharge space (spark _gap ) outside the cathode ray tube. Piezo electrode 6 ₁ , 6
₂ and 6 ₃ and further flows through the spark gap 3 ₁ via the low voltage electrode lead-out terminal 1 , and only a current higher than the discharge voltage of the spark gap 3 ₁ flows to ground 8 . The discharge starting voltage of the spark gap ₃₁ used here is generally about 1 kV in many cases. Therefore, voltages of 2kV or higher are directly connected to the low voltage electrodes 6 ₁ , 6 ₂ , 6 ₃
The low voltage electrodes 6 ₁ , 6 ₂ , 6
For example, the low voltage electrodes 6 ₁ , 6 ₂ , 6 _{3 to} which only 400V is normally applied are momentarily applied during discharge.
The voltage can reach up to 1kV, causing adverse effects such as malfunction and destruction of circuits.

At this time, if the spark gap 3 has a discharge starting voltage equal to the voltage applied to the low voltage electrodes 6 ₁ , 6 ₂ , 6 ₃ .
₁ , a discharge phenomenon occurs from the low voltage electrodes 6 ₁ , 6 ₂ , 6 ₃ to the ground 8 under normal usage conditions, and the instant of discharge becomes OV, which also causes the same adverse effect. Therefore, the spark gap 3 ₁ is set higher than the voltage of the low voltage electrodes 6 ₁ , 6 ₂ , 6 ₃ .

For this reason, conventional discharge countermeasures that release a voltage higher than the spark gap's discharge starting voltage to ground only when a discharge occurs on a low-voltage electrode from a high-voltage electrode do not allow the discharge of electricity attached to the low-voltage electrode due to the discharge phenomenon. It was not possible to completely eliminate the negative effects on circuits and peripheral equipment.

In addition, since the discharge countermeasure means is attached outside the cathode ray tube, the discharge starting voltage changes due to changes in humidity in non-sealed cathode ray tubes, making them unstable.

Furthermore, the current discharged to the low-voltage electrode flows to its attached circuits, causing damage to electrical circuits and peripheral equipment, and causing malfunctions.Also, when the discharge current flows, a strong magnetic field flows into the low-voltage electrode, attached circuits, and lead wires. If there is an integrated circuit such as a microcomputer nearby, it may malfunction or be destroyed.

As mentioned above, with conventional discharge countermeasures, the discharge current flows from the high voltage electrode to the low voltage electrode of the cathode ray tube electron gun, resulting in negative effects such as malfunction and destruction of the electric circuits and peripheral equipment used to operate the cathode ray tube. However, there were problems that required a great deal of labor and expense to repair and adjust them.

[Purpose of the invention]

The present invention was made in view of the above-mentioned problems.In order to prevent discharge from occurring from the high voltage electrode to the low voltage electrode, an auxiliary electrode is provided to directly ground the discharge from the high voltage electrode, and the discharge is conducted through the auxiliary electrode. The purpose of this invention is to provide a cathode ray tube electron gun that eliminates discharge to low voltage electrodes by letting the current escape, thereby preventing malfunctions and destruction of the electric circuits and peripheral equipment used to operate the cathode ray tube.

[Summary of the invention]

In the present invention, a plurality of electrodes are arranged at predetermined intervals through an insulating support rod, and at least one of the plurality of electrodes is a high voltage electrode to which a relatively high voltage is applied, and the other electrode is a high voltage electrode to which a relatively high voltage is applied. In a cathode ray tube electron gun which is a low voltage electrode to which a relatively low voltage is applied, at least one auxiliary electrode at ground potential having a predetermined discharge space between it and the high voltage electrode is opposed to the high voltage electrode; The predetermined discharge space is lower than the discharge starting voltage between a high voltage electrode and a low voltage electrode adjacent to this high voltage electrode, and is lower than the voltage difference between a normally used high voltage electrode and a low voltage electrode. This is an electron gun for a cathode ray tube, which is characterized by being raised high.

[Embodiments of the invention]

Next, an embodiment of an electron gun for a cathode ray tube according to the present invention will be described with reference to FIGS. 3 and 4. In the figure, the same reference numerals as in FIGS. 1 and 2 indicate the same parts.

As an electron gun for a cathode ray tube, the first grid 6 ₁ , the second grid 6 ₂ and the fourth grid 6 ₃ are low voltage electrodes to which a relatively low voltage is applied, and high voltage electrodes to which a relatively high voltage is applied. The third grid 5 ₁ and the fifth grid 5 ₂ which are electrodes are arranged in a unitary type with a predetermined interval between them via an insulating support rod 11, and high voltage electrodes 5 ₁ and 5 ₂ are used.
The discharge starting voltage is determined by the distances 9 ₁ , 9 2 , 9 ₃ between the high voltage electrodes 5 ₁ , _{5 2} and the low voltage electrodes 6 ₂ , _{6 3 adjacent} to the high voltage electrodes 5 ₁ , 5 2 . Conductive plate or rod-shaped auxiliary electrodes 7 ₁ , 7 ₂ are provided so that the discharge starting voltage is lower than that of the discharge space 10 .
₁ , 10 ₂ are constructed. In this case, the discharge space 10
In general cathode ray tube electron guns, the interval between ₁ and 10 ₂ is set to an interval corresponding to about 1.5 times the discharge starting voltage due to the voltage difference between the normally used high voltage electrode and low voltage electrode. Spacing 9 ₁ , 9 ₂ , 9 ₃ between 5 ₁ , _{5 2} and low voltage electrodes 6 ₂ , 6 ₃ , and the normally used high voltage electrodes 5 ₁ , 5 ₂ voltage and low voltage electrode 6
The interval is set at an intermediate interval between the interval corresponding to the discharge starting voltage due to the voltage difference between the ₂ and 6 ₃ voltages.

These auxiliary electrodes 7 ₁ , 7 ₂ are electrode lead wires 12 ₁ ,
12 ₂ , and the electrode lead wire 12 ₁ is grounded 8 via the external lead terminal 1 . In this case, auxiliary electrodes 7 ₁ , 7 ₂ and electrode lead lines 12 ₁ , 12 ₂
It may be integrally molded. In addition, the auxiliary electrode 7 ₁ ,
By making the side facing the high voltage electrodes 5 ₁ and 5 ₂ triangular in shape, the _sensitivity to receiving discharge can be increased.

In addition, the auxiliary electrodes 7 ₁ and 7 ₂ are fixed using an insulating support rod 11.
Plant it through or wrap it around it to fix it.
In this case, the positions of the auxiliary electrodes 7 ₁ and 7 ₂ are the low voltage electrodes 6
It is important that the distance between _the discharge spaces 10 ₁ and 10 ₂ be narrower than the distance between the discharge spaces 10 1 and 10 2 .

Further, the electrode lead lines 12 ₁ and 12 ₂ are connected to the auxiliary electrodes 7 ₁ ,
The electrode wire 12 ₁ is fixed to the fixed portion of the electrode wire 12 2 by electric welding, winding, or the like, and the other end of the electrode lead wire 12 ₁ is connected to the external lead terminal 1 by electric welding or the like. If there is not enough space in the external lead-out terminal 1, it may be connected to an external lead-out terminal connected to a grounding circuit such as a heater, or a new one may be installed.

With this structure, the high voltage electrode 5
The discharge current from the high voltage electrodes _{5 1} , 5 ₂ is transferred from the high voltage electrodes 5 ₁ , 5 ₂ to the auxiliary electrodes 7 ₁ , 7 ₂ , as shown by the broken line 4 in FIG.
Grounded 8 through electrode lead wires 12 ₁ and 12 ₂ ,
It does not flow to the low voltage electrodes 6 ₁ , 6 ₂ , 6 ₃ .

The above embodiment describes a unipotential type, but when there are multiple high voltage electrodes and each voltage is different, auxiliary electrodes are arranged at intervals and positions suitable for each high voltage electrode, and the electrode drawer is The present invention may be connected to a wire or an external lead-out terminal, and it goes without saying that it can also be applied to cathode ray tube electron guns of other structures.

〔Effect of the invention〕

As described above, according to the cathode ray tube electron gun of the present invention, discharge to the low voltage electrode can be prevented,
It can prevent malfunctions and damage caused by electrical discharge to the electrical circuits and peripheral equipment used to operate the cathode wire winding tube connected to the low voltage electrode.
Since the discharge space (space gap) is integrated with the electron gun and operates in a high vacuum, it is possible to obtain a discharge countermeasure that does not change the characteristics due to changes in the humidity of the outside air.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing conventional discharge countermeasures for cathode ray tubes, Fig. 1a is a plan view, Fig. 1b is a simplified cross-sectional view, and Fig. 2 is an explanation based on Fig. 1 showing how the discharge current flows. 3 and 4 are diagrams showing an embodiment of an electron gun for a cathode ray tube according to the present invention. FIG. 3 is an explanatory side view, and FIG. 4 shows how the discharge current flows in FIG. 3. FIG. DESCRIPTION OF SYMBOLS 1... External lead wire, 4... How discharge current flows, 5 ₁ , 5 ₂ ... High voltage electrode, 6 ₁ , 6 ₂ , 6 ₃ ...
Low voltage electrode, 7 ₁ , 7 ₂ ... auxiliary electrode, 8 ... ground, 10 ₁ , 10 ₂ ... discharge space, 11 ... insulating support rod.

Claims (1)

[Claims] 1 A plurality of electrodes are arranged at predetermined intervals through insulating support rods, and at least one of the plurality of electrodes is a high voltage electrode to which a relatively high voltage is applied, and the other electrode is a relatively high voltage electrode. In a cathode ray tube electron gun, which is a low voltage electrode to which a low voltage is applied, at least one auxiliary electrode at ground potential having a predetermined discharge space between it and the high voltage electrode is opposed to the high voltage electrode; The discharge space is lower than the discharge starting voltage between the high voltage electrode and the low voltage electrode adjacent to the high voltage electrode, and the voltage between the high voltage electrode and the low voltage electrode that is normally used. An electron gun for cathode ray tubes, characterized in that the electron gun is set to be higher than the difference.