KR100426569B1 - Electron gun for CRT - Google Patents

Abstract

The present invention relates to an electron gun for color cathode ray tubes.

The configuration of the present invention includes an electron gun including a main electrode comprising a cathode for emitting an electron beam toward a phosphor screen, an anode electrode on the screen side, and a focus electrode on the cathode side, and the position of the focus electrode is the center of the magnetic field, and the cathode ray A cathode ray tube including a VM (Velocity Modulation) coil mounted on the neck of a tube and synchronous with an image signal of a circuit, wherein the electron gun has two consecutive focus electrodes of the main electrode to which a fixed focus voltage is applied. More than one; When the sum of the lengths of the focus electrodes of the main electrodes including the two or more electrodes is 'L', and the sum of the intervals between the electrodes is 'g', the following equation, (g × 100) / L = 5 It characterized by satisfying the ~ 30 (%).

Therefore, according to the present invention, the structure of the electron gun is appropriately changed in accordance with the necessity of improving the focus on the screen, and the VM coil is applied to reduce the size of the screen spot in the horizontal direction by 15 to 30% than on the screen before the conventional structure change. The effect of improving the resolution can be obtained.

Description

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

The present invention relates to a color cathode ray tube, and more particularly, to an electron gun for a color cathode ray tube for reducing a spot diameter having a great influence on focus.

The electrodes of the in-line electron gun for the cathode ray tube are mutually perpendicular to the path through which the electron beam 13 passes so that the electron beam generated from the cathode 3 can be controlled in a constant intensity to reach the screen 16. Located at regular intervals.

Referring to the drawings in detail, as shown in FIG. 1, the first electrode 4 and the first electrode, which are common grids of three independent cathodes 3 and three cathodes 3 disposed at a predetermined distance from the cathodes, are separated from each other. The second electrode 5 and the third electrode (6), the fourth electrode (7), the fifth electrode (8), and the sixth electrode (9) arranged in a predetermined interval in the order of six electrodes ( 9) The upper part shows an inline electron gun configured in the order of the shield cup 10 with the BSC 11 attached to serve to fix the electron gun on the neck of the tube while electrically connecting the electron gun and the tube.

In addition, the electron gun emits electrons from the stem pin 1 by the heater 2 embedded in the cathode 3, and the electron beam 13 is controlled by the first electrode 4, which is a control electrode. The electron beam 13 is accelerated by the second electrode 5, which is an acceleration electrode, and is interposed between the second electrode 5, the third electrode 6, the fourth electrode 7, and the fifth electrode 8. The electron focus is partially focused and accelerated by the shear focusing lens formed.

A sixth electrode to which a variable voltage is applied in synchronization with the deflection signal to form a quadrupole lens for compensating astigmatism caused by the deflection yoke, and a sixth electrode 9 also referred to as a fogging electrode as a main lens forming electrode; The seventh electrode 10, also referred to as the anode electrode, causes the electron beam to focus and accelerate mainly, and passes through the shadow mask 15 provided on the inner surface of the fluorescent surface 16 to collide with the fluorescent surface 16 to emit light.

In addition, outside the electron gun, a deflection yoke 12 for deflecting the electron beam 13 emitted from the electron gun to the entire screen 17 is positioned to implement a screen.

Then, a VM (Velocity Modulation) (hereinafter referred to as a coil) 18, which acts in synchronism with the video signal of the circuit, is attached to the neck portion of the cathode ray tube equipped with the conventional electron gun.

The factors affecting the spot diameter on the screen among the design characteristics of the electron gun are lens magnification, spatial charge repulsion force, and spherical aberration characteristics of the main lens.

Among them, the influence of the spot diameter (D _x ) due to the lens magnification is determined by the basic voltage conditions, focal length, and the length of the electron gun, so there are few parts that can be used as a design element in the electron gun, and the effect is minimal.

The space charge repulsion force is the expansion of the spot diameter due to the reaction and collision between the electrons in the electron beam. To reduce the spot diameter (D _st ) due to the space charge repulsion force, the angle of the electron beam (hereinafter referred to as the divergence angle) is It is advantageous to design it to be large.

On the other hand, the spherical aberration characteristic of the main lens refers to the enlargement of the spot diameter (D _ic ) due to the difference in focal length between the electrons passing through the paraxial axis of the lens and the electrons passing through the circular axis, which is opposite to the space charge repulsion force. If the divergence angle at which the electron beam is incident on the main lens is small, a smaller spot diameter may be realized on the screen.

The spot diameter (D _t ) on the screen is generally expressed as the sum of three elements as shown in the following equation.

=

In particular, the best method is to reduce the spherical aberration while reducing the space charge repulsion force, and the best method is to enlarge the main lens and reduce the magnification of the spot due to the spherical aberration even when an electron beam with a large divergence angle is incident. Repulsive force can also be reduced, enabling small spots on the screen.

2 shows the change of the spot diameter according to the main lens diameter as an experimental result showing the above contents.

As can be seen from the graph shown in FIG. 2, the larger the main lens diameter, the smaller the magnification of the spot diameter due to the main lens spherical aberration, so that the spot diameter on the screen can be reduced.

In general, a fifth electrode to which a high voltage is applied and a sixth electrode to which a variable voltage is applied in synchronization with a deflection signal are collectively called a focus electrode, and the length of the focus electrode is a voltage ratio (%: focus / high pressure) of the electron gun. Decisions are an important factor.

The sixth electrode may be provided to compensate for the astigmatism of the deflection yoke, but the sixth electrode may not be applied when there is little need to improve the resolution and the sharpness of the periphery of the screen.

As a method of enlarging the main lens unit, there are a method of mechanically enlarging the hole diameter of the main lens forming electrode, and a method of deepening the depth of the electrostatic field control electrode body which performs a lens correction function.

However, the enlargement of the hole diameter of the mechanical electrode is almost impossible since there is a limiting factor of the neck diameter of φ 29.1 mm, which makes it difficult to improve the focus quality.

Therefore, in order to reduce the size of the spot on the screen and to improve the resolution, the Chassis circuit for driving the cathode ray tube is appropriately operated so that the differential signal of the image signal for scanning the electron beam on the screen is equipped with an electron gun. By applying in synchronization with the coils provided in the neck portion of the, the resolution and clarity on the screen can be improved by modulating the electron beam at a speed that is uniformly deflected by the deflection magnetic field of the deflection yoke.

3 briefly illustrates the operating principle of the Velocity Modulation (VM) coil.

However, in order to maximize the method of improving the resolution of the circuit, the length of the electrode to which the conventional fixed focus voltage is applied is short, and the interval is sufficiently sufficiently to effectively penetrate the speed modulated magnetic field by the current applied in synchronization with the image signal of the coil. Should be formed.

As described above, the structure of the conventional electron gun is inappropriate to maximize the effect of the coil.

In general, the center of the magnetic field generated by the coil is positioned near the fifth electrode to which the fixed and relatively high voltage is applied. The length of the electrode is increased to match the voltage ratio required by the design.

This also has the advantage of reducing costs and simplifying the production process as compared to the installation of small parts in series.

However, the structure of the electron gun by the simplified long electrode acts as a factor that hinders the improvement of the resolution by weakening the speed modulation effect by the magnetic field of the coil to improve the resolution.

Accordingly, an object of the present invention is to solve a conventional problem, and two or more focus electrodes to which a fixed focus voltage is applied are sequentially arranged among the main electrodes including the anode electrode and the focus electrode, and the fixed focus voltage is The purpose of the present invention is to maximize the action of the Velocity Modulation (VM) coil that operates in synchronization with the differential signal of the image signal by maintaining an appropriate interval between the applied focus electrodes.

1 is a schematic diagram of a typical cathode ray tube.

2 is a graph showing the change of the spot diameter by the main lens mirror.

3 is a view showing the operation principle of the VM (Velocity Modulation) coil.

Figure 4 is a view showing the structure of a conventional electron gun and the structure of an electron gun according to the present invention.

5 is a graph illustrating a change in the spot diameter of the screen by the focus electrodes and the VM coil.

(a) is a graph showing the number of intervals forming the intervals of the successive focus electrodes and the amount of reduction of the screen spot due to the speed modulation magnetic field of the VM coil.

(b) is a graph showing the reduction of the screen spot due to the interval width of each of the continuously installed focus electrodes and the speed modulation magnetic field of the VM coil.

(C) is a graph showing the amount of reduction of the screen spot caused by the speed modulation magnetic field of the VM coil with the electric field of the electron gun.

Figure 6 (a) is a view showing the structure of an electron gun according to the present invention.

(b) is a view including an electrode for applying a variable focus voltage to the structure of the electron gun according to the present invention.

Explanation of symbols on the main parts of the drawings

1; Stempin 2; Heater

18: VM coil 24: first electrode

25; second electrode 26: third electrode

27: fourth electrode 28: focus electrode to which a fixed voltage is applied

29: ninth electrode 31: focus electrode to which a variable voltage is applied

The present invention for achieving the above object, the electron gun including a main electrode consisting of a cathode for emitting an electron beam toward the phosphor screen, an anode electrode on the screen side and a focus electrode on the cathode side, and the position of the focus electrode A cathode ray tube comprising a VM (Velocity Modulation) coil which is a center of a magnetic field and is mounted on the neck portion of the cathode ray tube to operate in synchronism with a video signal of a circuit, wherein the electron gun is formed of a main electrode to which a fixed focus voltage is applied. The focus electrodes consist of two or more in succession; When the sum of the lengths of the focus electrodes of the main electrodes including the two or more electrodes is 'L', and the sum of the intervals between the electrodes is 'g', the following equation, (g × 100) / L = 5 It characterized by satisfying the ~ 30 (%).

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

In order to maximize the method of improving the circuit resolution of the VM coil, the length of the focus electrode to which the fixed focus voltage at which the center of the magnetic field generated by the VM coil is located is increased to match the high voltage ratio, and the image signal of the VM coil is increased. Sufficient electrode spacing should be formed to effectively penetrate the rate-modulated magnetic field by the applied current in synchronization with

Accordingly, the electron gun main lens structure of the present invention has an electrode having an opening common to three electron beams similar to the conventional electron gun structure, a plate-shaped electrostatic field control electrode body having three electron beam through holes, and a cap shape as shown in FIG. The electrodes are stacked and configured, and the electrodes are electrically connected through a welding process, so that a variable voltage synchronized with a high voltage and a deflection signal is applied.

The focus electrode is conventionally classified into an electrode for applying a variable focus voltage and an electrode for applying a fixed focus electrode, among main electrodes including an anode electrode on the screen side and a focus electrode on the cathode side.

Among them, two or more focus electrodes to which a fixed focus voltage is applied are arranged.

4 (a) and 4 (b) are conventional electron gun structures, and FIG. 4 (c) is an electron gun structure according to the present invention, in which an electron gun structure in which focus electrodes 28 receiving a fixed focus voltage are successively arranged is arranged. to be.

4 (d) also shows a structure of the electron gun according to the present invention, in which the focus electrode 31 to which the variable focus voltage is applied and the focus electrodes 28 to which the fixed focus voltage is applied are arranged in succession. The structure of is shown.

4C corresponds to a cathode 23 to which an image signal is applied, a second electrode 25 which collects electrons emitted from the cathode and pulls the electrons toward the screen direction and a predetermined or more image signal to which an electron beam is applied to the cathode. When no voltage is applied, the first electrode 24 is disposed to prevent the emission of electrons. The third electrode 26 applies a relatively high voltage and the fourth electrode 27 receives a relatively low voltage. And focus electrodes 28a, 28b, 28c that apply a relatively high fixed voltage.

The main lens is formed to scan the electron beam on the screen by the ninth electrode 29 to which high voltage is applied, thereby forming the screen of the cathode ray tube.

FIG. 4D illustrates a quadrupole lens having a structure similar to that of FIG. 4C to apply a variable focus voltage in synchronization with a deflection yoke deflection signal and to compensate for astigmatism caused by the deflection yoke magnetic field. Another eighth electrode 31 is disposed.

The main lens is formed to scan the electron beam on the screen by the eighth electrode 31 and the ninth electrode 29 to which high voltage is applied, thereby forming a screen of the cathode ray tube.

6 is a structure of an electron gun having a focus electrode for applying a fixed focus voltage according to the present invention.

The main electrode is composed of an anode electrode 29 and a focus electrode 28. The focus electrode 28 is composed of an electrode 31 for applying a variable focus voltage and an electrode 28 having a fixed focus voltage. .

Among them, two or more focus electrodes 28 to which a fixed focus voltage is applied are arranged consecutively as shown in FIGS. 4C and 4D of 28a, 28b and 28c, and successively arranged focus electrodes 28 are provided. The sum of the lengths of L has a value of 4 mm or more and 30 mm or less.

In this case, when the sum of the formed intervals g1 and g2 between the successively arranged focus electrodes 28 is g, the following equation, (g × 100) / L = 5 to 30 (%) is satisfied. Do it.

Experimental results of the focus electrode 28 receiving a fixed focus voltage satisfying the above equation are shown in the graph of FIG. 5.

5 illustrates a change in the spot diameter of the screen by the focus electrodes receiving a fixed focus voltage and a coil acting in synchronization with the differential signal of the image signal.

FIG. 5A shows the number of intervals of the electron gun electrodes, in particular, the focus electrodes receiving a fixed focus voltage located at the center of the working magnetic field of the coil, that is, the fifth electrode 28a and the sixth electrode 28b of FIG. 4. , And a graph showing the number of gaps formed like the seventh electrode 28c and the amount of reduction of the screen spot by the speed modulating magnetic field of the coil. As the number of intervals increases, the effect increases.

FIG. 5 (b) shows the width of each formed gap of the focus electrodes 28 and the amount of reduction of the screen spot due to the speed modulating magnetic field of the coil. The effect of the coil when the gap is about 0.6 to 1.2 mm is shown. It can be seen that is maximized.

In addition, Figure 5 (c) is a graph showing the relationship between the electric field of the electron gun and the speed modulation magnetic field of the coil, it can be seen that there is a section proportional to the electron gun inserted in the cathode ray tube.

Therefore, when analyzing the data of FIG. 5 as described above, the number of intervals of the focus electrodes 28 should be one or more, and the width of each interval between the focus electrodes 28 is most effective at a level of 0.6 to 1.2 mm. The longer the field of the electron gun is, the better the effect is.

As a result of fabricating and evaluating the sample under the above conditions, the spot size on the screen may have a reduction effect of about 15 to 30% in the horizontal direction compared to the conventional electron gun.

Therefore, according to the present invention, in order to reduce the spot diameter having a large influence on the focus, the same voltage is applied by dividing into two or more electrodes while maintaining the overall length of the focus electrode to which the fixed focus voltage is applied, and applying the same voltage. By forming the gap between 0.6 and 1.2 mm, the size of the screen spot in the horizontal direction can be reduced by 15 to 30%, and it can be applied in a small cost and in a short period of time, thereby improving the quality of the focus early.

Claims (2)

An electron gun comprising a main electrode consisting of a cathode which emits an electron beam toward the phosphor screen, an anode electrode on the screen side, and a focus electrode on the cathode side, and the position of the focus electrode is centered on the magnetic field and mounted on the neck portion of the cathode ray tube In the cathode ray tube comprising a VM (Velocity Modulation) coil that is synchronized with the video signal of the circuit, The electron gun includes two or more focus electrodes of the main electrode to which a fixed focus voltage is applied; When the sum of the lengths of the focus electrodes of the main electrodes including the two or more electrodes is 'L', and the sum of the intervals between the electrodes is 'g', the following equation, (g × 100) / L = 5 Electron gun for color cathode ray tube, characterized in that it satisfies ~ 30 (%). The method of claim 1, Wherein L is the following formula, 4mm <L <30mm electron gun for a color cathode ray tube, characterized in that.