KR20020017590A - Electron gun in-line type for color cathode ray tube - Google Patents

Abstract

PURPOSE: An in-line electron gun for a color CRT is provided to realize a stable screen by preventing a stray and achieving a stable brightness in the screen with reliably radiating a cathode current by cutting off a leakage current of the cathodes and thermal deformation of the triode part. CONSTITUTION: An electron gun includes a triode part and lenses. The triode part comprises a plurality of cathodes for emitting electron beams, a control electrode for controlling amount of emission of the electron beams, and an acceleration electrode. The lenses have two or more electrodes to focus the electron beams to a screen. An end part of a predetermined numbers of eyelets arranged in a row of one hermetic structure body of the triodes at constant intervals is installed to be lower than surface of the hermetic structure body(120) in screen direction.

Description

Electron gun in-line type for color cathode ray tube}

The present invention relates to the structure of the three-pole portion of the electron gun for cathode ray tube, in particular, in the high-definition triode, the leakage of current between the cathodes together with the thermal deformation of the hermetic cathode support, the first electrode and the second electrode by the heat supplied from the heater. The present invention relates to an inline electron gun for a color cathode ray tube to perform stable luminance and stray prevention on a screen through stable radiation of a cathode current by blocking a.

In general, the electrodes of the in-line electron gun for cathode ray tubes are spaced apart from each other such that the electron beam generated from the cathode is perpendicular to the path through which the electron beam passes, so that the electron beam generated in the cathode can be controlled to reach a screen. The cathode is attached with an oxide for emitting electrons at the end of the screen direction, and a heater is installed inside to supply heat for electron emission.

1 is a structural diagram of a conventional color cathode ray tube, in which the first grid electrode 2 and the first grid electrode, which are common grids of three independent cathodes 1 and three cathodes 1 disposed at a predetermined distance from the cathodes, are arranged. The second grid electrode 3, the third grid electrode 4, the fourth grid electrode 5, the lower electrode 6a, the upper electrode 6c, and the guide electrode disposed at regular intervals from the grid electrode. 6b) and the second acceleration and focusing electrode 6 having the correction electrode 9, the correction acceleration 9 therein, and the second acceleration configured in the order of the shield cup 8 for shielding the deflection leakage magnetic field thereon. And an inline electron gun composed of a focusing electrode 7.

At this time, in order to obtain a constant current value so that the cut-off voltage of the electron gun must be the same, different voltages are supplied to the cathodes, and the electron guns are not shown inside the cathode 1, but a built-in heater is installed and The electrons are emitted by the heating of the electrons, and the emitted electrons are controlled by the first grid electrode 2, which is a control electrode, so that the electron beams 11, 12, 13 are controlled through the second grid electrode 3, which is an acceleration electrode. A shadow provided on the inner surface of the fluorescent surface 15 by accelerating the electron beams 11, 12, 13 and passing through the upper electrode 6a of the first acceleration and focusing electrode, which is the main lens forming electrode, and the second acceleration and focusing electrode 7. The deflection yoke 16 which impinges on the fluorescent surface 15 through the mask 14 and emits a fluorescent substance, and deflects the electron beams 11, 12, 13 emitted from the electron gun to the entire screen fluorescent surface 15 outside the electron gun. Is located.

FIG. 2 is a schematic diagram of a hermetic structure of a conventional cathode portion, in which the cathode portion of FIG. 1 is enlarged, and three cathodes 1, 1b, for emitting electron beams of R (red), G (green), and B (blue), respectively. 1c) and a heater for supplying heat to the cathode are embedded, oxide is coated on the surface of the cathode in the screen direction, and the heater generates heat by the current supplied through the stem pin, and the temperature is usually 720 to 760. In this case, in order for the electrons emitted by the high heat to reach the screen through the electrode, the inside of the cathode ray tube must be maintained in vacuum, and the general degree of vacuum of the cathode ray tube is 5x10 < -4 >

In order to release electrons from the oxide coated on the cathode as described above, the carbonate in the oxide must be completely separated. This process is performed before the getter flashing to improve the vacuum degree since the vacuum degree in the cathode ray tube is reduced. In addition, heat deformation gradually occurs in the triode including the cathode by the high-heat heater for electron emission. The cathode expands toward the control electrode, and the control electrode moves toward the acceleration electrode, thereby making the radiation dose of the initial electron beam uneven. After a certain period of time, a sufficient amount of heat is transferred to each part of the electron gun, and the change between the electrodes is insignificant, and the emission of the electron beam changes stably. This is called an over shoot.

The electrons emitted from the cathode are controlled by the first grid electrode 2 as the control electrode, and the electron beams 11, 12 and 13 are controlled, and the electron beams 11, 12 and 13 by the second grid electrode 3 as the acceleration electrode. ) Is subjected to preliminary focusing while passing through the third grid electrode 4, the fourth grid electrode 5, and the lower electrode 6b of the first acceleration and focusing electrode, which constitute the shear focusing lens. The electron beams 11, 12, 13 are focused while passing through the first acceleration and focusing electrode 6 constituting the lens and the second acceleration and focusing electrode 7, and a shadow mask 14 installed on the inner surface of the fluorescent surface 15. Pass through to form an electron beam spot on the fluorescent surface 15, and the electron beam spot is scanned by the deflection yoke 16 to form a screen.

The focusing action of the center electron beam 12 and the side electron beams 11 and 13 passing through the asymmetric large-diameter main lens is not the same, in particular the focusing action of the side electron beam Different focusing in the horizontal and vertical direction.

On the other hand, the astigmatism correcting electrode 10 provided between the second acceleration and focusing electrode 7 and the shield cup 8 may be configured to connect the first acceleration and focusing electrode 6 and the second acceleration and focusing electrode 7 to each other. It acts to weaken the focusing action in the vertical direction of the electron beams 11, 12, 13 while passing.

Recently, according to the technology of cathode ray tube, high resolution and high brightness electron guns are required. Therefore, in order to improve the resolution of cathode ray tube, it is necessary to reduce the electron beam through hole of the control electrode, and also to achieve high brightness. Impregnated cathodes, which have a higher current density and longer life than oxide cathodes, have been applied. In general, impregnated cathodes are also called I-Cathodes. In order to emit electrons, a temperature about 200 degrees higher than that of a general oxide cathode is required.

The voltage applied to each cathode for color reproduction of the electron gun is adjusted according to the reduction of the electron beam through hole of the control electrode of the high-resolution electron gun. This voltage cuts off the voltage at the time when the electron beam is emitted from the cathode. the cutoff voltage generally has to have a thin thickness around the hole of the control electrode in order to have the same cutoff voltage while maintaining the electron beam through hole of the control electrode, and when the cutoff voltage is lowered, the cathode for color reproduction is reduced. Difficult to adjust the applied voltage makes it difficult to manufacture a monitor or television chassis and increases the production cost.

Therefore, it is very important to maintain the cutoff voltage in the high-resolution electron gun so that the thickness around the control electrode electron beam through hole is thin. However, in order to reduce the thickness around the electron beam through hole of the control electrode, there are some limitations. In some cases, the thickness of the raw material should be changed. This thinner raw material is more sensitive to the thermal change caused by the heater than the conventional raw material, and moreover, the problem becomes more significant when the impregnated cathode is used for extending the life.

FIG. 3a illustrates an example of applying a conventional oxide cathode, and FIG. 3b illustrates an example of applying an impregnated cathode. When the impregnated cathode is applied to a control electrode in which the raw material is thin, as in FIG. The double wall of the sleeve and eyelet is formed and the gap is narrowed so that the heat generated by the heater is transmitted to the sleeve so that the heat radiated from the sleeve can not escape out of the eyelet and concentrates toward the control electrode. This is because the eyelet height L1 is similar to the electron emitting surface height L4 of the cathode.

Accordingly, the control electrode sensitive to thermal deformation, which is thinner than 200 degrees of heat compared to the general oxide cathode, is severely changed, which acts as a critical deterrent to stable radiation of the electron beam.

Another problem is that the diameter Di 'of the oxide disk portion of the impregnated cathode is wider than that of the normal oxide cathode, and the size of the sleeve is also increased since the diameter is generally about 30% larger.

Due to the above reason, the diameter of the eyelets is also increased. The enlarged eyelet diameter (Do ') makes the eyelet gap g1 between R, G, and B shown in FIG. 2 very narrow, and the gap between the narrowed eyelets is There is a high possibility of causing leakage current between cathodes to materials such as Ba and Al emitted in the cathode activation process, which is one of the fatal defects of cathode ray tubes.

In order to solve the above problems, the present invention blocks the thermal deformation of the three poles and current leakage between the cathodes by the heat supplied from the heaters, thereby inducing stable radiation of the cathode currents, thereby preventing stable brightness and stray on the screen. An object of the present invention is to provide an electron gun for color cathode ray tubes.

In order to achieve the above object, the present invention is characterized in that the end of the screen direction of the predetermined number of eyelets arranged side by side at a predetermined interval on one of the hermetic structure lower than the surface of the screen direction of the hermetic structure.

In addition, the eyelet is characterized by preventing the leakage current between the eyelets by maximizing the distance through the upper surface of the hermetic structure between the eyelets by inserting the end of the screen direction in the hermetic.

1 is a structural diagram of a conventional color cathode ray tube;

2 is a Hermetic structure diagram of a conventional negative electrode portion,

Figure 3a is an illustration of a conventional oxide cathode application,

Figure 3b is an illustration of a conventional impregnated cathode application,

4A to 4C are structural diagrams of an electron gun for a cathode ray tube to which the present invention is applied.

<Description of the symbols for the main parts of the drawings>

110: upper surface of the hermetic structure

120: surface in the screen direction of the hermetic structure

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

4A to 4C are structural diagrams of an electron gun for a cathode ray tube to which the present invention is applied.

First, in FIG. 4A, three eyelets are arranged side by side at a predetermined interval in one hermetic structure, and each eyelet is installed lower than the surface 120 in the screen direction of the end of the hermetic structure in the screen direction.

When the conventional oxide cathode of FIG. 3a is applied, L3 <L2 <L1, while FIG. 4A of the present invention applies the formula L3 + (L2-L3) x 0.2 ≤ L1 ≤ L2.

Here, L1 refers to the distance from the cathode eyelet end (stem direction) of the hermetic structure to the opposite end of the eyelet, and L2 from the eyelet end (stem direction) to the upper surface of the hermetic (screen direction). L3 is the distance from the eyelet tip (stem direction) to the lower surface of the hermetic (stem direction).

Next, FIG. 4B illustrates a state in which the eyelet end and the upper surface 110 of the hermetic structure are coincided with each other, and FIG. 4C shows a shape in which the end of the eyelet is opened and inserted into the hermetic structure.

4A to 4C, as shown in the three examples of FIG. 4C, the end portions of the three eyelets are disposed not to be higher than the upper surface 110 of the hermetic structure, and the heat is increased by about 200 degrees higher than that of the conventional oxide cathode. By removing the eyelets around the existing cathodes, the heat trapped inside the eyelets and cathodes is concentrated on the thinner control electrodes for high resolution, eliminating the rapid thermal deformation of the thinner control electrodes, thereby avoiding the sudden thermal deformation of the entire electron gun. The heat spreads quickly, reducing the stabilization time for thermal deformation between the electrodes.

In addition, FIG. 4C illustrates that when each screen direction eyelet end is lowered in the maximum stem direction to maximize the distance through the upper surface 100 of the hermetic structure between the eyelets to prevent leakage current between the eyelets disposed in the hermetic structure. Since the eyelet is difficult to be stably supported by the hermetic because there are few parts supported by the metic, the end of the eyelet screen direction is inserted into the hermetic to support the eyelet.

As described above, the present invention is configured such that the end of the eyelet's screen direction does not protrude to the upper surface of the hermetic in the hermetic structure to not only disperse high heat concentrated on the electrode, but also to prevent leakage current due to a narrow gap between the eyelets. By effectively blocking, it is possible to achieve stable radiation at the cathode to remove serious defects caused by screen stray or leakage current and to provide a stable screen with little change in luminance, thereby improving the resolution of the entire screen area.

Claims (4)

In the electron gun having a plurality of cathodes for emitting an electron beam, a three-pole portion consisting of a control electrode and an acceleration electrode for adjusting the radiation amount of the electron beam, a lens composed of two or more electrodes for focusing the electron beam on the screen, An inline electron gun for a color cathode ray tube, characterized in that the end of the screen direction of the predetermined number of eyelets arranged side by side at a predetermined interval of the one of the three poles is not higher than the surface of the screen direction of the hermetic structure. The method of claim 1, wherein the predetermined number of eyelets An inline electron gun for color cathode ray tubes, characterized in that the screen direction end portion is inserted into the hermetic to prevent the leakage current between the eyelets by maximizing the distance through the upper surface of the hermetic structure between the eyelets. The method of claim 2, Electron gun for color cathode ray tube, characterized in that the end of the eyelet screen direction in the hermetic structure does not protrude to the upper surface of the hermetic. The method of claim 1, wherein the eyelet is An electron gun for a color cathode ray tube, wherein L3 + (L2-L3) x0.2≤L1≤L2. L1: length from the end of the negative eyelet of the hermetic structure (stem direction) to the opposite end of the eyelet, L2: The distance from the end of the eyelet (stem direction) to the upper surface of the hermetic (screen direction), L3: Distance from the end of eyelet (stem direction) to the lower surface of the hermetic (stem direction)