KR100625526B1 - Electron gun for color CRT - Google Patents

Abstract

Disclosed is a color gun tube electron gun for minimizing noise generated by using a dynamic voltage in correcting astigmatism using a dynamic voltage.

To this end, the present invention is characterized in that the bead glass embedding depth of the second focusing electrode to which the fixed focusing voltage and the variable dynamic voltage are overlapped and applied is shorter in a predetermined range than the bead glass embedding depth of the other electrode.

Accordingly, the frequency band of the noise generated by the second focusing electrode can be moved to a high frequency above the audible frequency, thereby minimizing the actual audible noise.

Halo, Astigmatism, Dynamic Voltage, Quadrupole Lens

Description

Electron gun for color cathode ray tube {Electron gun for color CRT}             

1 is a configuration diagram of an electron gun for a general color cathode ray tube,

2 is a configuration diagram of an astigmatism correction electrode,

2a is an overall coupling degree,

2B is a configuration diagram of the first focusing electrode;

2C is a configuration diagram of the second focusing electrode,

3 is a block diagram of an electron gun for a color cathode ray tube according to the present invention,

4 is a detailed view of an electrode according to the present invention;

4A is a detailed view of a second focusing electrode,

4B is a detailed view of electrodes other than the second focusing electrode,

5 is a graph showing the relationship between the bead glass embedding depth of the electrode and the noise,

6 is a graph showing the relationship between the bead glass embedding depth and the frequency of the electrode.

*** Explanation of symbols for the main parts of the drawing ***

2: cathode 3: control electrode

4 acceleration electrode 5 'first focusing electrode

5 ": 2nd focusing electrode 5c: Bead glass embedding part of a 2nd focusing electrode

6: anode 7: bead glass

The present invention relates to an electron gun for a color cathode ray tube, and more particularly, to an electron gun structure for minimizing noise generated by using a dynamic voltage in correcting astigmatism using a dynamic voltage.

In general, cathode ray tubes are the most widely used display devices for observation of oscilloscopes or radars, including television receivers.

The cathode ray tube is focused on the fluorescent surface of the screen by passing a shadow mask, which is a color-selective electrode, in a state in which the electron beam emitted from the electron gun is deflected in the horizontal and vertical directions by the deflection yoke.

In this case, the red, green, and blue electron beams must be converged on one screen to realize the image. In the electron gun, the red, green, and blue cathodes are arranged side by side. A concentrated deflection yoke is applied.

That is, the deflection yoke compensates for mis-convergence at the periphery of the fluorescent surface by providing a pincushion type as the vertical deflection field and a barrel type as the horizontal deflection field. It does not need additional devices for concentrating three-color electron beams such as concentrators (dynamic and convergence), so it is very economical and easy to adjust the concentration, contributing to the improvement of quality and performance of the color receiver.

However, in the deflection method using the above-mentioned magnetic concentration, in the center of the screen, the focus of the electron beam is increased in the vertical direction due to the influence of the two-pole and four-pole magnetic fields, so that the focus is overfocused. In addition to the high ellipsoidal core portion long in the horizontal direction, a low luminance halo in the vertical direction is generated.

That is, the two-pole magnetic field deflects the electron beam in the horizontal and vertical directions, and the four-pole magnetic field focuses the electron beam in the vertical direction and diverges in the horizontal direction. This shorter distance results in a halo phenomenon where the vertical direction of the beam is raised convexly on the screen.

Such a halo deteriorates the screen resolution, especially the resolution of the peripheral part, thereby degrading the screen. Therefore, various methods for correcting the halo have been proposed.

Thus, the general color cathode ray tube electron gun shown in FIG. 1 will be described as an example of the electron gun according to the prior art, and an example of the halo correction according to the prior art will be described with reference to the halo correction electrode shown in FIG. 2.

As shown in FIG. 1, a general electron gun for a color cathode ray tube includes a three-pole part for controlling an emission amount of an electron beam, and a main lens part for focusing and finally accelerating an electron beam generated from the three-pole part. The three-pole part includes a heater 1 embedded therein. It consists of three cathodes 2 arranged in an in-line shape, a control electrode 3 and an acceleration electrode 4 for controlling and accelerating hot electrons emitted from the cathode 2, and the main lens portion is a tripolar portion. A focusing electrode 5 for focusing the electron beam generated therefrom and an anode 6 for finally accelerating the electron beam, and each electrode 3, 4, 5, 6 is sequentially arranged on the bead glass 7. It is purchased.

Here, the voltage applied to each of the electrodes 3, 4, 5, and 6 is differentiated in order to pull the electron beam in the direction of the fluorescent film and to focus each electron beam to one point. The electrostatic lens is formed, and the control electrode 3 is grounded, a high voltage of 500 to 1000 V is applied to the acceleration electrode 4, 25 to 35 kV is applied to the anode 6, and an anode is applied to the focusing electrode 5. An intermediate voltage of 20 to 33% of the voltage is applied.

As a predetermined voltage is applied to each of the electrodes 3, 4, 5, and 6 in such a state, an electrostatic lens is formed by a potential difference between the focusing electrode 5 and the anode 6 to form a three-pole portion ( 2) (3) (4) focuses the electron beam generated on the center of the screen.

In this case, in order to reproduce an image, electron beams must be sequentially scanned on each area of the screen, and the above-described self-focusing deflection yoke is applied.

In addition, in the application of the self-focused deflection yoke, when the deflection angle increases, that is, the halo, which is a low luminance part, is generated toward the periphery of the screen.

FIG. 2 shows an electrode structure for calibrating halo disclosed in US Pat. No. 5,061,881 of Matsushita, Japan. The focusing electrode 5 is divided into two electrodes 5 ', 5 "and the first focusing electrode ( 5 ') has an elongated rectangular electron beam through-hole 5a, and a second focusing electrode 5 "is formed with a quadrangular rectangular electron beam through-hole 5b to form a four-pole lens at the periphery of the screen. And to correct astigmatism.

In addition, a fixed focusing voltage is applied to the first focusing electrode 5 'and a focusing voltage that changes in synchronization with the deflection amount of the electron beam is applied to the second focusing electrode 5 "to form a 4-pole lens. The overfocus in the vertical direction can be reduced by the diverging action of the pole lens.

That is, in general, a high voltage of 7 to 8 kW is required for the focusing voltage, and the voltage applied to the second focusing electrode 5 " is parabolic (Parabola) in synchronization with the deflection of the electron beam to this focusing voltage (7 to 8 kW). The dynamic voltage of about 300 to 1000 V, which is changed to the shape of (), is superimposed, and the dynamic voltage becomes 300 to 1000 V when the electron beam is deflected toward the periphery of the screen, and 0 V when deflected at the center of the screen.

Accordingly, the electron beam is focused only by the main lens when deflected to the center of the screen, and focused by the main lens and quadrupole lens when deflected to the periphery of the screen.

In addition, since the quadrupole lens is focused in the horizontal direction and divergent in the vertical direction, the electron beam is focused in a good state in the horizontal direction and underfocused in the vertical direction. It is possible to offset the difference in the bias scan which is in the overfocus state.

However, the quadrupole lens electron gun according to the related art can realize the spot shape of the electron beam in a substantially circular shape in the entire screen, thereby realizing a high-quality screen as the resolution of the screen is improved, but increases in synchronization with the deflection frequency. Vibration occurs in the second focusing electrode due to the increment of the voltage, and this vibration has a problem that noise is generated through the electrode embedding part of the second focusing electrode because there are many low frequency bands which are mainly an audible frequency band.

In particular, in recent years, as the quadrupole lens electron gun is becoming more common, the problem of noise becomes very serious.

Accordingly, the present invention has been proposed in view of the above, and an object of the present invention is to provide an electron gun for color cathode ray tube, which can solve the problem of noise caused by dynamic voltage in using a quadrupole lens electron gun to implement a high quality screen. have.

In order to achieve the above object, the electron gun for a color cathode ray tube according to the present invention includes a three-pole portion for generating an electron beam, and a first focusing electrode and a second focusing electrode for focusing the electron beam generated from the three-pole portion. A constant voltage is applied to the first focusing electrode and a variable voltage is applied to the second focusing electrode. The bead glass embedding depth of the second focusing electrode is in a predetermined range than the bead glass embedding depth of the other electrode. It is characterized by a short configuration.

Preferably, the bead glass embedding depth of the second focusing electrode is characterized in that the shorter than the shortest of the bead glass embedding depth of the other electrode is configured to be 0.2mm or more short.

In this case, when the vibration occurs according to the dynamic voltage increment, the frequency band can be moved to a high frequency above the audible frequency, thereby effectively reducing noise.

And, there may be a plurality of embodiments of the present invention, hereinafter will be described in detail with respect to the most preferred embodiment.

This preferred embodiment allows for a better understanding of the objects, features and advantages of the present invention.

In addition, in drawing used for description, about the component same as FIG. 1 and FIG. 2, the same code | symbol is attached | subjected, and the overlapping description may be abbreviate | omitted.

3 is a configuration diagram of an electron gun for a color cathode ray tube according to the present invention, FIG. 4 is a detailed view of an electrode according to the present invention, FIG. 4A is a detailed view of a second focusing electrode, and FIG. 4B is an electrode other than the second focusing electrode. 5 is a graph showing the relationship between the bead glass embedding depth and the noise of the electrode, Figure 6 is a graph showing the relationship between the bead glass embedding depth and the frequency of the electrode.

3 and 4, the electron gun for the color cathode ray tube according to the present embodiment generates a correction magnetic field on the quadrupole lens as much as the astigmatism generated when the electron beam is deflected to the periphery of the screen. In order to minimize the noise caused by the increment of the dynamic voltage applied to the second focusing electrode 5 ", the bead glass embedding depth L1 of the second focusing electrode 5" is the other electrode 3 (4). It is shorter than the bead glass embedding depth L2 of (5 ') (6).

That is, in the present embodiment, the bead glass embedding depth of each electrode is almost the same, whereas in the present embodiment, the bead glass embedding depth of the second focusing electrode 5 " to which the dynamic voltage is applied is the other electrodes 3, 4 and 5 There is a difference in constructing shorter than the bead glass embedding depth of ') (6).

At this time, the bead glass embedding depth of the second focusing electrode 5 "should be set to an optimal depth that can cover all the noises varying according to the amount of application of the dynamic voltage, and the bead of the second focusing electrode 5" It is preferable to set the frequency band of the noise emitted from the glass buried portion 5c to a depth capable of moving at a high frequency above the audible frequency, and when applied to each electrode, at least the bead glass of the second focusing electrode 5 ". When the embedding depth is made 0.2 mm or more shorter than the bead glass embedding depth of the other electrodes 3, 4, 5 ′, and 6, the optimum state is achieved.

Referring to the operation of the electron gun for color cathode ray tube according to the present invention configured as described above are as follows.

First, since the electron gun applied to the present invention is an electron gun for forming a quadrupole lens for implementing a high quality screen, the focusing electrode is divided into two parts, and a fixed focusing voltage is applied to the first focusing electrode 5 'and the second focusing electrode 5 Is applied to overlap the dynamic voltage which is variable to the fixed focus voltage.

Accordingly, during operation of the cathode ray tube, vibration of the second focusing electrode 5 "is inevitably generated due to an increase in the variable dynamic voltage, and the vibration is embedded in the bead glass 5c of the second focusing electrode 5". Radiation to noise through has been described above.

However, since the variable voltage is continuously applied to the second focusing electrode 5 "while the cathode ray tube is in operation, the vibration generated in the second focusing electrode 5" cannot be essentially eliminated, but the audible frequency band of the noise is audible. Moving above the frequency band (16-20000 Hz band) can minimize the actual audible noise.

5 is a graph showing the relationship between the bead glass embedding depth and the noise of the electrode, it can be seen that the level of noise gradually decreases as the bead glass embedding depth of the electrode is short, Figure 6 is the bead glass embedding depth of the electrode As a graph showing the relationship between frequencies, it can be seen that as the bead glass embedding depth of the electrode becomes shorter, the frequency moves to a higher frequency band.

This means that as the bead glass embedding depth of the electrode is shortened, the frequency moves to a high frequency band above the audible frequency band, and thus the level of noise gradually decreases.

Accordingly, since the bead glass embedding depth of the second focusing electrode 5 '' to which the present invention is applied is configured to be at least 0.2 mm shorter than the bead glass embedding depth of the other electrodes 3, 4, 5 'and 6, the cathode ray The frequency band of the noise generated by the increment of the dynamic voltage during the operation of the tube can be moved to a higher frequency band than the audible frequency band, thereby minimizing the actual audible noise.

As described above, according to the present invention, it is possible to solve the problem of noise due to the dynamic voltage while using the quadrupole lens electron gun, thereby improving productivity and reliability.

In addition, although specific embodiments of the present invention have been described and illustrated above, it is obvious that the present invention may be variously modified and implemented by those skilled in the art.

Such modified embodiments should not be individually understood from the technical spirit or the prospect of the present invention, and such modified embodiments should fall within the appended claims of the present invention.

As described above, the present invention can make the bead glass embedding depth of the second focusing electrode shorter than the bead glass embedding depth of the other electrode to shift the frequency band of the noise generated in the second focusing electrode to a high frequency above the audible frequency. Therefore, there is an effect that the actual audible noise is minimized.

Claims (2)

A color cathode ray including a triode which generates an electron beam, a first focusing electrode and a second focusing electrode that focus the electron beam generated from the triode, and a bead glass in which the first focusing electrode and the second focusing electrode are embedded and fixed. In a conventional gun, A constant focusing voltage is applied to the first focusing electrode, a focused focusing voltage and a dynamic voltage of a variable voltage are applied to the second accelerating electrode, The embedding depth of the second focusing electrode embedded in the bead glass is smaller than the embedding depth of an electrode other than the second focusing electrode. The method of claim 1, The bead glass embedding depth of the second focusing electrode is 0.2 mm or more shorter than the shortest of the bead glass embedding depth of the other electrode, the electron gun for color cathode ray tube.

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