JP2001155663A - Color cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color cathode ray tube which prevents the increment of the contact resistance due to the damage of conductive layer contacted to bulb spacer when processing withstand voltage needed application of high voltage, and the occurrence of mis-convergence synchronized with parabola voltage. SOLUTION: In a color cathode ray tube 1, in which the bulb spacer 34 electrically connected to the acceleration electrode G6 of the electron gun 31 is contacted with the conductive layer 2 formed in inner face 30 of the neck part 30 of a funnel 23, and the beam distortion due to the deflection is corrected by applying a parabola voltage to the focus electrode G5 of electron gun 31, the thickness of the conductive layer 2 of the contact part 2a of bulb spacer 34 and the conductive layer 2 is 5-10 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube, and more particularly, to optimizing the thickness of a conductive layer made of a conductive material such as interior graphite so that the conductive layer which is in contact with a valve spacer during withstand voltage processing is damaged. The present invention relates to a color cathode-ray tube in which the occurrence of light is prevented.

[0002]

2. Description of the Related Art Along with the progress of the information society, a color cathode ray tube 21 suitable for displaying images such as a computer terminal display and a high definition television has a structure and functions as shown in FIG. That is, it has a bulb 25 in which a glass panel 22 and a glass funnel 23 are integrally joined by a frit glass 24, and inside the panel 22, phosphors emitting green, blue, and red emit dots or stripes. A shadow mask 27 having a large number of electron beam passage holes formed at a predetermined interval behind the phosphor screen 26 is welded and fixed to a mask frame 28. The shadow mask structure is locked and fixed by panel pins 29 embedded in the inner wall of the panel 22. On the inside of funnel 23,
A conductive layer 33 made of a conductive material such as graphite is formed from the cone portion 32 to the neck portion 30. An electron gun 31 that emits three electron beams is disposed in a neck portion 30 of the funnel 23, and a valve spacer 34 that communicates with an acceleration electrode is made of an elastic metal and has a conductive layer 33.
Are in contact with each other. A deflection yoke 35 is provided outside the funnel 23 from the neck 30 to the cone 32. Then, a high voltage is externally applied to the acceleration electrode through the conductive layer 33 to accelerate the electron beam.
Electrons corresponding to blue and red are irradiated on the respective phosphor screens 26 to emit light, thereby displaying an image. In particular, the convergence around the screen is improved by combining an in-line type electron gun that emits three electron beams arranged in a horizontal line in the horizontal scanning direction and a self-convergence deflection magnetic field.

In recent color cathode ray tubes, improvement in brightness (luminance) and resolution of a display screen is particularly required. As the former countermeasure, the operating voltage is increased along with the increase in the luminance of the phosphor, the improvement in the transmittance of the shadow mask, the increase in the current of the electron beam, and the like. As the latter countermeasure, there is a development of a multistage focusing electron gun in which focus electrodes are multiplexed, and an improvement in focus characteristics of the electron gun. In the inline self-convergence method, since the deflection magnetic field is distorted, the beam diameter around the screen increases, and the resolution around the screen tends to deteriorate. For this reason, an AC voltage (parabolic voltage) synchronized with the horizontal deflection voltage is superimposed on the focus voltage and applied to a focus electrode (for example, a G5 electrode in a multistage focusing type electron gun and a G3 electrode in a normal electron gun). The beam diameter around the screen is improved, and the resolution around the screen is improved.

FIG. 7 shows an example of an electrode configuration of a multistage focusing electron gun. The electron gun 31 includes a heater 36, a cathode 3
7, a shield case 38 electrically connected to the first grid electrode G1, the second grid electrode G2, the third grid electrode G3, the fourth grid electrode G4, the fifth grid electrode G5, the sixth grid electrode G6, and G6. G2 and G4, and G
3 and G5 are respectively connected by a lead connector or the like in the neck portion 30. A heater voltage is applied to the heater 36, G1 is grounded, a voltage of about several thousand volts is applied to G2 and G4, and a high voltage input terminal 39 provided on the funnel 23 and a conductive layer 33 are applied to G6. 20 to 3 via the valve spacer 34 and the shield case 38.
A high voltage of 0 KV is applied, and a medium voltage of about 30% of the voltage applied to G6 is applied to G3 and G5.

[0005]

In a conventional color cathode ray tube 21, a conductive layer 3 made of graphite or the like applied to a neck 30 is used.
3 was generally 3 to 4 μm thick. For this reason, when the discharge current at the time of the withstand voltage process flows from the electron gun side to the high voltage input terminal 39 side, a contact portion between the valve spacer (BS) 34 as a contact portion and the conductive layer 33 (hereinafter, referred to as a contact portion).
It is called BS contact. Due to the high contact resistance of (2), Joule heat was increased, and as a result, the conductive layer 33 was altered and damaged, and the BS contact had an extremely large resistance value. For this reason, the conventional completed color cathode ray tube 21
Is operated, the conductive layer 3 is connected via the high voltage input terminal 39.
The high voltage applied to 3 is applied to the shield case (SC) 38 and the G6 electrode after a voltage drop at the contact resistance portion of the BS contact. For this reason, the voltage of the main lens constituted by G6 and G5 becomes lower than the setting. At the same time, the parabolic voltage (AC) applied to the focus electrode (G5) is applied to the G
6- Superimposed on high voltage applied to SC-BS. For this reason, a potential difference corresponding to the parabola voltage is generated between the SC and the conductive layer, and the G6 potential fluctuates by the parabola voltage.
(Shown by a broken line in FIG. 7) is formed. This pseudo lens 4
Due to 0, the trajectory of the electron beam (particularly, the side beam) is deflected, causing a non-predetermined phosphor to emit light, and a convergence (Cg) shift synchronized with the parabola voltage occurs. The cause of this problem is an increase in contact resistance due to damage to the conductive layer in the BS contact.

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above problems, and an object of the present invention is to prevent a conductive layer in contact with a valve spacer from being damaged at the time of withstand voltage processing for applying a high voltage, thereby preventing an increase in contact resistance. Another object of the present invention is to provide a color cathode ray tube in which a convergence deviation synchronized with a parabola voltage is prevented.

[0007]

According to the color cathode ray tube of the present invention, a valve spacer, which is electrically connected to an acceleration electrode of an electron gun, is in contact with a conductive layer formed on an inner surface of a neck portion of a funnel. In a color cathode ray tube that applies a parabola voltage to correct the electron beam distortion due to deflection, the contact resistance between the bulb spacer and the conductive layer increases due to the discharge during the withstand voltage processing, and the parabola voltage increases on the accelerating electrode side A means for preventing the image from being superimposed on the image. According to this configuration, the parabola voltage does not overlap on the accelerating electrode side, so that a pseudo lens is not formed, and the occurrence of a convergence shift synchronized with the parabola voltage can be prevented.

The color cathode ray tube of the present invention is characterized in that the means is a thickness of a conductive layer at a contact portion between the bulb spacer and the conductive layer, and the thickness is set to a predetermined thickness. According to this configuration, the thickness of the conductive layer at the contact portion is appropriately formed, so that the conductive layer at the contact portion between the valve spacer and the conductive layer is damaged during the withstand voltage process of applying a high voltage, and the contact resistance is reduced. Can be prevented from increasing.
Therefore, the parabola voltage applied to the focus electrode does not overlap on the accelerating electrode side, a pseudo lens is not formed, and a convergence shift synchronized with the parabola voltage can be prevented from occurring.

Further, in the color cathode ray tube of the present invention, the thickness of the conductive layer at the contact portion between the bulb spacer and the conductive layer is 5-10.
μm (more preferably 7 to 10 μm). According to this configuration, the thickness of the conductive layer at the contact portion is sufficient, so that the conductive layer at the contact portion between the valve spacer and the conductive layer is damaged and the contact resistance increases during the withstand voltage process of applying a high voltage. Can be prevented. Therefore, the parabola voltage applied to the focus electrode does not overlap on the accelerating electrode side, a pseudo lens is not formed, and a convergence shift synchronized with the parabola voltage can be prevented from occurring. Further, since the thickness of the conductive layer is set to a maximum of 10 μm, a decrease in the adhesive strength between the inner surface of the funnel and the conductive layer can be prevented, and peeling of the conductive layer can be prevented.

The conductive layer is mainly composed of graphite.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a valve spacer electrically connected to an acceleration electrode of an electron gun contacts a conductive layer formed on the inner surface of a neck portion of a funnel, and applies a parabolic voltage to a focus electrode of the electron gun. This is a color cathode ray tube designed to correct the distortion of the electron beam due to deflection.In particular, the contact current between the bulb spacer and the conductive layer deteriorates due to the discharge current during withstand voltage processing, and the contact resistance increases excessively. Means for preventing the parabola voltage from being superimposed on the accelerating electrode side. This means:
Including various things, for example, the material of the conductive layer of the contact portion,
Optimization of the thickness and the like is an effective means. According to this configuration, it is possible to prevent the conductive layer at the contact portion between the valve spacer and the conductive layer from being damaged and increase the contact resistance during the withstand voltage process of applying a high voltage, so that the parabola voltage applied to the focus electrode is reduced. There is no overlap on the accelerating electrode side, and therefore no pseudo lens is formed, and it is possible to prevent the occurrence of a convergence shift synchronized with the parabola voltage.

An embodiment of a color cathode ray tube according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a color cathode ray tube 1 of the present invention. The same parts as those of the conventional color cathode ray tube 21 shown in FIG. The color cathode ray tube 1 of the present invention is equipped with, for example, a multistage focusing electron gun 31. And funnel 2
The conductive layer 2 containing graphite as a main component is formed with a predetermined thickness from the cone part 32 of the third part 3 to the inner surface of the neck part 30. Particularly, the thickness of the conductive layer 2 in the contact portion 2a with the valve spacer 34 is 5 to 10 μm.
The conductive layer 2 is applied with a conductive paint mainly containing a conductive powder such as graphite, titanium oxide, iron oxide and the like, and a binder such as potassium silicate and sodium silicate by an interior graphite coating device, and then dried. It is formed by this.

The conductive layer 2 is formed by coating, for example, as follows. FIG. 2 is a configuration diagram of the interior graphite coating apparatus 3, in which an injection nozzle 4 is provided along the inside of the opening of the funnel 23.
The conductive paint 6 in the application tank 5 is injected while moving the
Is applied. Further, by fixing the injection nozzle 4 and rotating the funnel 23 around the axis, the funnel 2
3 can also be applied to the inner surface. At that time, the excess conductive paint 6 is discharged from the neck portion 30 and enters the recovery container 7 provided at the lower portion. After the conductive paint 6 in the collection container 7 is stored in the collection tank 9 by the pump 8, it is supplied to the application tank 5 by the pump 10 and reused. Thereafter, the conductive paint 6 applied on the inner surface of the funnel 23 is dried, and unnecessary conductive paint 6 near the opening end of the neck portion 30 is washed and removed to obtain a predetermined conductive layer 2.

The conductive layer 2 can be formed on the inner surface of the neck portion 30 by coating as follows. For example, FIG.
As shown in (1), the application means 13 composed of a disc-shaped sponge 12 attached to one end of the movable shaft 11 and impregnated with the conductive paint is inserted into the neck portion 30 and moved in the axial direction of the neck portion 30. , Or by rotating around an axis.

The funnel 23 on which the conductive layer 2 is formed
And a face panel 22 on which a phosphor screen and a mask structure are formed
After the electron gun 31 is sealed in the valve 25 sealing the above, the gas is exhausted while being heated to a predetermined temperature by the exhaust device. In the latter half of the evacuation process, the electrodes of the electron gun 31 are heated and degassed by high-frequency induction heating, and then the heater 36 is energized to heat the cathode 37, and the alkaline earth metal applied to the cathode 37 is heated. Is decomposed into oxides, and after exhausting sufficiently, the exhaust pipe of the valve is heated and melted and sealed. Next, a getter (not shown) installed in the bulb is heated and scattered to form a getter film on the inner wall of the bulb, and the inside of the bulb is maintained at a high vacuum. Further, a stabilizing process such as activation of a cathode and a withstand voltage process such as a knocking process are performed. The knocking process removes fine projections on the surface of each electrode constituting the electron gun, burrs generated by press molding, and a stray emission source such as barium (Ba) attached to the electrode surface by applying a high voltage to remove the source. Things are mainstream. A typical method is an intermediate electrode float method, and as shown in FIG. 4, a heater 36, a cathode 37, G1, G2,
This is a method in which G4 is grounded, a high voltage is applied to G6, and G3 and G5 as intermediate electrodes are electrically floated to maintain a relatively high float voltage and spark.

The present inventor has prototyped a color cathode ray tube in which the thickness of the conductive layer 2 is variously changed, and superimposes the contact resistance of the BS contact and the G6 electrode after the withstand voltage treatment by the above-mentioned intermediate electrode float method. The parabolic voltage, the convergence deviation amount, the adhesive strength of the conductive layer, and the like were measured, and the effect of the thickness of the conductive layer on these characteristics was examined. The results shown in FIG. 5 were obtained. FIG. 5A shows B after the withstand voltage processing.
4 shows the relationship between the contact resistance value of the S-contact and the thickness of the conductive layer. In the figure, the contact resistance is substantially constant when the thickness of the conductive layer is about 5 μm or more, but when the thickness is less than 5 μm, the contact resistance sharply increases, suggesting that the conductive layer is altered or damaged.
Next, FIG. 5B shows the relationship between the parabola voltage superimposed on the high voltage applied to the G6 electrode (acceleration electrode) side and the thickness of the conductive layer. In the figure, the thickness of the conductive layer is approximately 5 μm.
Above m, the parabolic voltage superimposed is about 0 volts, but when it is thinner than 5 μm, the parabolic voltage sharply increases, suggesting an increase in contact resistance. Since there is a capacitance C between the G5 and G6 electrodes, when a new contact resistance R is formed, a CR series circuit is equivalently formed, and the parabolic voltage is superimposed on the G6 electrode side. If the contact resistance can be neglected, the parabola voltage does not overlap on the G6 electrode side. Next, FIG. 5C shows the relationship between the amount of misconvergence and the thickness of the conductive layer. In the figure, when the thickness of the conductive layer is about 5 μm or more, misconvergence can be ignored, but when the thickness is less than 5 μm, misconvergence cannot be ignored. This is due to the formation of a pseudo lens due to the superposition of the parabola voltage. Next, FIG.
Indicates the relationship between the adhesive strength of the conductive layer and the thickness of the conductive layer.
In the figure, when the thickness of the conductive layer is approximately 10 μm or less, the adhesive strength of the conductive layer to the inner surface of the funnel is almost constant, but as the thickness increases more than 10 μm, the adhesive strength decreases.
It is easy to peel off. The peeled pieces may cause fatal defects in the color cathode ray tube, such as short-circuiting between the electrodes of the electron gun or blocking the slot holes of the mask.

From the above results, it can be seen that B caused by withstand voltage processing
The thickness of the conductive layer for preventing the contact resistance of the S contact from increasing and for preventing the conductive layer from peeling off is preferably 5 to 10 μm. In particular, 7 to 10 μm is optimal.

In the above embodiment, the focus electrode G
A color cathode ray tube equipped with a multi-stage focusing electron gun having a focusing electrode G and an accelerating electrode G6 has been described.
Needless to say, the present invention can also be applied to a color cathode ray tube equipped with a normal electron gun having the electron gun 3 and the acceleration electrode G4.

[0019]

As described above, the color cathode ray tube of the present invention is provided with means for preventing the conductive layer at the contact portion between the bulb spacer and the conductive layer from being damaged and increasing the contact resistance. In addition, the parabola voltage applied to the focus electrode does not overlap on the accelerating electrode side, a pseudo lens is not formed, and the occurrence of convergence deviation synchronized with the parabola voltage can be prevented. Further, since the thickness of the conductive layer is set to a maximum of 10 μm, a decrease in the adhesive strength between the inner surface of the funnel and the conductive layer can be prevented, and peeling of the conductive layer can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a color cathode ray tube having a conductive layer according to the present invention.

FIG. 2 illustrates an example of a conductive layer forming apparatus.

FIG. 3 is a diagram illustrating a method of forming a conductive layer on a neck portion.

FIG. 4 is a view for explaining a withstand voltage process for applying a high voltage;

5A and 5B are diagrams for explaining the influence of the thickness of a conductive layer, and FIG.
(B) shows the relationship with the parabolic voltage superimposed on the high voltage applied to the G6 electrode (acceleration electrode), (c) shows the relationship with the amount of misconvergence generated, and (d) shows the conductive layer with respect to the inner surface of the funnel. 2 shows the relationship with the adhesive strength of the sample. )

FIG. 6 is a sectional view of a conventional color cathode ray tube.

FIG. 7 is a diagram showing an electrode configuration of a conventional color cathode ray tube electron gun.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color cathode ray tube 2 Conductive layer (graphite etc.) 2a Contact part 23 Funnel 30 Neck part 31 Electron gun 32 Cone part 34 Valve spacer G5 Focus electrode G6 Acceleration electrode

Claims (5)

[Claims] A valve spacer, which is electrically connected to an accelerating electrode of an electron gun, is in contact with a conductive layer formed on the inner surface of a neck portion of a funnel, and applies a parabolic voltage to a focus electrode of the electron gun to deflect an electron beam by deflection. In the color cathode ray tube adapted to correct the distortion, a means is provided for preventing the contact resistance between the bulb spacer and the conductive layer from increasing due to the discharge during the withstand voltage treatment and preventing the parabola voltage from being superimposed on the accelerating electrode side. A color cathode ray tube. 2. The collar according to claim 1, wherein said means is a conductive layer thickness at a contact portion between the valve spacer and the conductive layer, and the conductive layer thickness is set to a predetermined thickness. Cathode ray tube. 3. The color cathode ray tube according to claim 2, wherein said conductive layer has a thickness of 5 to 10 μm. 4. The color cathode ray tube according to claim 2, wherein said conductive layer has a thickness of 7 to 10 μm. 5. The color cathode ray tube according to claim 3, wherein a main component of the conductive layer is graphite.