KR100274878B1 - Electron Gun for Color Cathode Ray Tube - Google Patents

Abstract

A cathode control electrode and a screen electrode forming a triode, first, second, third, and four focus electrodes sequentially installed from the screen electrode, and a final acceleration electrode disposed adjacent to the fourth focus electrode; An AC dynamic focus voltage synchronized with a deflection signal is applied to a fourth focus electrode, and the AC dynamic focus is applied to the first and third focus electrodes adjacent to the screen electrode by being dropped by a voltage drop means. A constant voltage is applied to the two focus electrodes.

Description

Electron gun for colored cathode ray tube

The present invention relates to an electron gun, and more particularly, to an electron gun for a color cathode ray tube in which an applied state of a voltage for each electrode constituting each electron gun is improved.

Typically, the color cathode ray tube uses the principle of the triode, and an example is shown in FIG. 1.

As shown in the drawing, a panel 11 having a fluorescent film having a predetermined pattern formed therein, a shadow mask frame assembly 12 having a shadow mask 12a spaced apart from the fluorescent film by a predetermined distance, and the funnel Sealed with (11), it is comprised by the neck part 13a and the cone part 13b provided with the funnel 13 provided with the inline electron gun 16 and the deflection yoke 17, respectively. At the end of the neck portion 13a, a lead pin 18 for applying a predetermined voltage to each electrode constituting the electron gun 16 is provided. The deflection yoke 17 is a self-convergence deflection yoke having a barrel-type vertical deflection magnetic field and a pincushion-type horizontal deflection magnetic field for self-convergence of the electron beam emitted from the in-line electron gun 16. Oak is used.

In the cathode ray tube configured as described above, the electron beam emitted from the electron gun is selectively deflected by the deflection yoke 17 to excite the phosphor of the fluorescent film to form an image. In this process, as shown in FIG. 2, the electron beam emitted from the electron gun 16 is a non-uniform magnetic field of the deflection yoke, that is, the pincushion type horizontal deflection magnetic field 22 is perpendicular to the electron beam 24 when the electron beam is deflected from side to side. Direction and deflected in the horizontal direction, the barrel-type vertical deflection magnetic field 21 emits the electron beam 25 in the horizontal direction when the electron beam is deflected in the vertical direction to make the halo 26 at the periphery of the fluorescent film. . Therefore, the shape of the electron beam landing on the front surface of the fluorescent film becomes uneven and the focus characteristic is deteriorated, so that the resolution of the image cannot be improved.

In order to solve such a problem, conventionally, in order to prevent the spot of the electron beam from being distorted in the periphery of the fluorescent film, that is, the screen film, the resolution is reduced, a plurality of focus electrodes of the electron gun are divided into a plurality of focus electrodes close to the final accelerating electrode and the adjacent or A quadrupole lens is formed between the divided focus electrodes, and a dynamic focus voltage synchronized with a deflection signal is applied to at least one focus electrode forming the quadrupole lens. As a result, a dynamic focus method is used, which compensates for the distortion of the electron beam cross section due to the non-uniform magnetic field of the deflection yoke when the electron beam is deflected, thereby obtaining a uniform focus characteristic on the entire surface of the fluorescent film.

An example of such a dynamic focus electron gun is disclosed in US Pat. No. 4,945,2284. The electron gun electrically connects at least two focusing electrodes spaced apart by a predetermined distance to form an electron lens by using a resistor, and receives a predetermined voltage from a flyback transformer of a cathode ray tube device, and focuses one side of the focusing electrode. It has a structure to apply AC voltage. The electron gun causes the A.C voltage applied to the focusing electrode of one side to be applied to the focusing electrode of the other side by applying the reduced A.C voltage through the capacitance between the resistor and the electrode to form an electron lens between the focusing electrodes.

Another example of the conventional dynamic focus electron gun is disclosed in US Pat. No. 5,519,290, which is shown in FIG.

As shown, it includes a cathode (K), which is an electron emission source, and first, second, third, fourth, fifth, six, and seventh grids G1 -G7 that are sequentially installed from the cathode to form an electron lens. The electrode is provided with an electron beam through hole arranged in an inline shape, the elongated electron beam through hole (H1) and the elongated electron beam through hole (H2) on the opposite surfaces of the fifth and sixth grid (G5) (G6) Are formed respectively. In addition, a dynamic focus voltage Vf synchronized with a deflection signal is applied to the third and sixth grids G3 and G6, and a voltage applied to the sixth electrode G6 is applied to the fifth electrode G5. AC voltage is effectively reduced and applied using the capacitance between R) and the fifth and sixth grids G5 and G6.

The dynamic focus electron gun constructed as described above has the following problems.

first; The electron guns have a cost reduction effect compared to the circuit configuration of the cathode ray tube set by the two-division voltage application method, but are caused by a resistor or capacitance for the amplitude of the focus voltage of the AC component applied in synchronization with the deflection signal. Since the AC voltage is reduced and the ratio of the amplitude of the voltage applied to the other electrode is about 50%, a high voltage (400 V) is required to correct the distortion of the electron beam spot at the periphery of the screen of the cathode ray tube. Therefore, when constructing a circuit, the output of a high waveform voltage is required as compared to the conventional method, and there is a concern about electron beam unbalance at both ends of the screen of the cathode ray tube. In addition, when combined with multi-scanning technology, which is essential in the recent monitor market, where various resolutions are required, resolution such as phase shift due to frequency variation of deflection yoke is caused. Will deteriorate.

Second, during the manufacturing process of the color cathode ray tube device, a change in the intrinsic characteristics of the capacitance between the electrodes and the resistance provided between the fifth and sixth grids may occur, which makes it difficult to control the AC voltage applied to the fifth grid. This may cause deterioration of focus characteristics in the fluorescent film.

third; Since the resistor connected between the fifth and sixth grids is installed inside the cathode ray tube, the resistance cannot be changed or changed.

fourth; The electron gun of the conventional cathode ray tube device can adjust the DC focus voltage and the AC focus voltage applied to the circuit, respectively, but the dynamic focus electron gun applies one AC voltage to the fifth and sixth grids by using a resistor. When the focus voltage difference between the center vertical component and the horizontal component of the is changed, the focus characteristic may be degraded at the center or periphery of the screen.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a ratio of a focus voltage of an AC component applied to a focus electrode in synchronization with a deflection signal and a voltage applied to another focus electrode by reducing the focus voltage by a resistor or capacitance. It is an object of the present invention to provide an electron gun for a color cathode ray tube that can increase the focus characteristic of the cathode ray tube and improve the focus characteristic of the entire screen.

1 is a cross-sectional view of a typical cathode ray tube,

2 shows a non-uniform magnetic field of deflection yoke,

3 is a cross-sectional view of a conventional electron gun showing a state where voltage is applied to an electrode.

4 is a cross-sectional view of a cathode ray tube according to the present invention;

5 is a view schematically showing a state in which a voltage is applied to an electron gun for a color cathode ray tube according to the present invention;

6 is a view showing a waveform of the AC dynamic focus voltage and the reduced voltage of the electron gun for color cathode ray tube according to the present invention;

FIG. 7 shows a correlation between an AC dynamic focus voltage and an AC dynamic focus voltage depressurized by a resistor and an electron beam scanned on a screen; FIG.

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

31; Cathode 32; Control electrode

33; Screen electrode 34; First focus electrode

35; Second focus electrode 36; Third focus electrode

37; A fourth focus electrode 38; Final acceleration electrode

VFD; AC dynamic focus voltage VF; VFD voltage reduced by resistor

In order to achieve the above object, the present invention provides a cathode structure which is an electron emission source, and at least three or more focus electrodes and final acceleration electrodes arranged inline to form an electron lens that focuses and accelerates an electron beam emitted from the cathode structure. And a voltage drop means for dropping an AC voltage in synchronization with the deflection signal and applying it to the focus electrode on the other side, and a constant voltage is applied to the focus electrode located at the center.

Other features of the present invention include a cathode, a control electrode and a screen electrode, which are electron emission sources constituting the triode, and a plurality of focus electrodes arranged inline and forming an electron lens for focusing and accelerating the electron beam emitted from the cathode. A screen having an acceleration electrode, applying an AC dynamic focus voltage synchronized with a deflection signal to at least one of the focus electrodes, and applying the AC dynamic focus voltage to the at least one focus electrode by a voltage drop means; It is characterized in that applied to the focus electrode adjacent to the electrode.

In still another aspect of the present invention, a cathode control electrode and a screen electrode forming a tripolar portion, first, second, three, and four focus electrodes sequentially installed from the screen electrode, and adjacent to the fourth focus electrode are provided. An AC dynamic focus voltage synchronized with a deflection signal is applied to the fourth focus electrode, and the AC dynamic focus is applied to the voltage drop means to the first focus electrode and the third focus electrode adjacent to the screen electrode. It is dropped and applied by, characterized in that the constant voltage is applied to the second focus electrode.

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

An electron gun for a cathode ray tube according to the present invention is enclosed in a neck portion of a funnel sealed with a panel on which a fluorescent film is formed to emit an electron beam to excite the fluorescent film, and an embodiment thereof is illustrated in FIG. 4.

As shown, the first, second, third, and fourth focus electrodes 34 are sequentially provided from the cathode 31, the control electrode 32, the screen electrode 33, and the screen electrode 33. 35, 36, 37, and a final acceleration electrode 38 disposed adjacent to the fourth focus electrode 37. The number of focus electrodes provided sequentially from the screen electrode 33 is not limited by the above embodiment, and is preferably at least three or more that can form an electron lens for focusing. Each electrode constituting the electron gun is formed with an electron beam passing hole for forming an electron lens. That is, three electron beam through holes are arranged inline in each electrode, and have various shapes according to the shape of the electron lens to be formed. As an example, in order to form the quadrupole lens by applying the AC dynamic focus voltage described below, an elongated electron beam passing hole is formed on the exit side of the opposing third focus electrode 36 and the incident side of the fourth focus electrode 37, respectively. A quadrupole lens can be formed by forming the 36a and the transverse electron beam through hole 37a. The shape of the electron beam through hole for forming the quadrupole lens is not limited to the above-described embodiment, and any shape can be used as long as the quadrupole lens can be formed.

And a predetermined voltage is applied to each electrode configured as described above by the voltage applying means shown in Figs. 3 and 5, which will be described in detail as follows.

The first constant voltage VS1 of −100 V to 0 V is applied to the control electrode 31, and the second constant voltage VS2 of 0 V to 1000 V is applied to the screen electrode 32. As shown in FIG. 6, an AC dynamic focus voltage VFD is applied to the fourth focus electrode 37, and the AC dynamic focus voltage is applied to the final acceleration electrode 38. The voltage corresponds to 20 to 40% of 40KV. The AC dynamic focus voltage VFD applied to the fourth focus electrode 37 is applied to the first and third focus electrodes 34 and 36 by the voltage drop means 40. VF) is applied. The focus voltage VF applied to the first and third focus electrodes 34 and 36 is lower than the AC dynamic focus voltage VFD within a range of 20 to 40% of the enoud voltage.

The voltage drop means 40 includes a resistor 41 for dropping the AC dynamic focus voltage VFD and applying it to the first and third focus electrodes 34 and 36. The resistor 41 is provided between the fourth focusing electrode 37 and the third focusing electrode 36 inside the neck portion or is installed in the neck portion of the cathode ray tube to apply a voltage to each electrode of the electron gun. It may be installed in a socket (not shown) coupled with. When the resistor 41 is installed in the socket, the depressurized focus voltage is applied to the first and third focus electrodes 34 and 36. When the resistor 41 is installed in the socket, a variable resistor may be used.

In the above embodiment, two focus electrodes (first and third focus electrodes) to which the voltage reduced by the resistor 41 is applied are described as an example, but the present invention is not limited thereto. The number of focus electrodes to which the voltage reduced by 41 is applied can be increased or decreased. As in the above embodiment, when the focus electrode, that is, the focus electrode to which the voltage VF depressed by the resistor 41 is applied, is the first and third focus electrodes 34 and 36, the first focus electrode 34 is used. ) Is preferably positioned on the side opposite to the screen electrode 33 in the arrangement order. In addition, the application of the reduced pressure to the first focusing electrode 34 applies the reduced pressure through the resistor 41 to the third focusing electrode 36, and the third focusing electrode 36 and the first focusing electrode ( 34) is connected through the separate connector 42 inside the neck portion or applied through a lead pin fixed to the neck portion.

The second focusing electrode 35 is applied with a constant voltage VS3 which is not synchronized with the deflection signal. The constant voltage VS3 is applied higher or lower than the reduced voltage within 20 to 40% of the enwood voltage VE. Here, it is preferable to apply the same voltage as the voltage VS2 applied to the screen electrode 33 to the second focus electrode 25.

In addition, each electrode constituting the electron gun has a voltage applied thereto, so that the interval between the fourth focus electrode 37 and the final acceleration electrode 38 is preferably maintained at 0.90 to 1.20 mm in consideration of the capacitance acting between the electrodes. Preferably, the distance between the screen electrode 33 and the first focus electrode 34 is maintained at 0.45 to 0.6 mm. The interval between the third and fourth focus electrodes forming the quadrupole lens is preferably maintained at 0.65 to 1.0 mm.

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

The color cathode ray tube device according to the present invention has a predetermined voltage as shown in FIGS. 5 and 6 in the electron emitting unit including the cathode 31 constituting the electron gun and the electrodes and the deflection yoke constituting the electron gun. As applied, an electron lens is formed between each electrode. In particular, a dynamic quadrupole lens is selectively formed between the third and fourth focus electrodes 36 and 37 according to the dice, and is variable between the fourth focus electrode 37 and the final acceleration electrode 38. The main lens is formed.

In the process of forming the electron lens as described above, in the process of scanning the electron beam to the periphery of the screen, the fourth focus electrode 37 is synchronized with the deflection signal as shown in FIG. A parabolic type AC dynamic focus voltage (VFD) is applied, and a low pass filter effect is applied to the first and third focus electrodes 34 and 36 through a resistor 41 which is a voltage drop means 40. The AC dynamic focus voltage Spp having a predetermined amplitude Spp is applied by the action of the resistor and the capacitance circuit.

In the electron gun, the effect of applying the AC voltage decompressed using the resistor 41 can be expressed as follows.

Dpp = Vm.EXP (jωt)

Spp = [α] Vm.EXP {j (ωt) + ψ}

[α] = √ 1+ (ωC 1 R) 2/1 + ω 2 (C 1 + C 2) 2 R 2

ψ = tan ^-1 -ωC ₂ R / 1 + ω ² C ₁ (C ₁ + C ₂ ) R ²

{Dpp; Amplitude of AC Dynamic Focus Voltage Applied to Fourth Focus Electrode

Spp; The amplitude of the reduced AC focus voltage applied to the third focus electrode through the resistor

[α]; Superimposed ratio of phases

ψ; Phase difference

C _1, C ₂ ; Capacitance between Electron Gun Electrodes

R; Resistance of resistor

ω; Angular frequence}

From the above equation, the amplitude (Dpp) of the parabola-type AC dynamic focus voltage is set to the ratio of the smooth-pose, that is, [α] by the low pass filter effect between the resistor and the electron gun electrode mounted inside or outside the neck of the cathode ray tube. It can be seen that the amplitude Spp of the decompressed focus voltage VF is reduced and the phase difference is generated at ψ.

As described above, the amplitude Spp of the depressurized parabola-type AC dynamic focus voltage may be expressed as follows when the center portion and the peripheral portion of the screen are deformed.

VFD (ζ) = VF1 + Dpp.ζ ²

VF (ζ) = VF1 + 1- [α] / 3 * Dpp + [α] Dpp.ζ ²

{VFD; Focus voltage applied to the fourth focusing electrode

VF; Focus voltage applied to the third focusing electrode

VF1; A focus voltage ζ applied to the fourth focus electrode at the center of the screen of the cathode ray tube; Relative position of the electron beam on the screen (center zone ζ = 0 horizontal both ends ζ = ± 1)}

Therefore, as shown in FIG. 7, when the electron beam is positioned at the center portion (ζ = 0) of the screen, the voltage of the third focus electrode 36 becomes relatively higher than the voltage of the fourth focus electrode 37 and the periphery of the screen of the electron beam. When deflected by (ζ = ± 1), the voltage of the third focusing electrode 36 becomes relatively lower than the voltage of the fourth focusing electrode 37. Thus, as the electron beam is deflected toward the periphery of the screen, the voltage difference between the third focusing electrode 36 and the fourth focusing electrode 37 becomes larger, so that the action of the quadrupole lens formed between the two electrodes causes a non-uniform deflection field. Astigmatism of the electron beam can be corrected.

In this process, [α] is filtered by the amplitude (Dpp) of the parabola-type AC dynamic focus voltage (VFD) applied from the circuit of the cathode ray tube set and the capacitance between the resistor 41 and the electrode to depressurize the AC voltage (VF). The smaller the ratio of the amplitude Spp, i.e., the larger the voltage difference between the two electrodes, the stronger the quadrupole lens becomes.

[α] ∝γ, C = ε ₀ .S / L

γ = C1 / C1 + C2 = L2 / L1 + L2

{γ = attenuation ratio, C1 _, C2 = capacitance between electrodes constituting each electron gun, L, L1 _, L2 = mechanical distance between electron gun electrodes with each capacitance, S; Mechanical cross section of the opposing surface between electrodes}

The reduced AC voltage passing through the resistor 41 is applied to the first focus electrode facing the screen electrode 33 from the above equation, and is applied to the screen electrode between the first and third focus electrodes 34 and 36. When a constant voltage VS3 equal to the voltage VD2 is applied, the capacitance between the third and fourth focus electrodes 36 and 37 is constant, but the capacitance C2 between the first focus electrode and the third focus electrode 36 is constant. Is increased by the sum of the capacitance C2a between the first focusing electrode and the second focusing electrode and the capacitance C2b between the second focusing electrode and the third focusing electrode. Therefore, the value of γ becomes small, thereby reducing the [α], that is, the superimpose ratio. Therefore, the amplitude (Spp) of the reduced AC dynamic focus voltage (VF) through the circuit of the cathode ray tube set is 50% to 40% compared to the amplitude (Dpp) of the AC dynamic focus voltage applied to the fourth focus electrode (37). It can be lowered below, and the attenuation ratio of the amplitude can be increased by varying C1, C2 or changing the mechanical cross-sectional area between L1, L2 and the electrode from the above equation. As a result, a better rectified waveform can be obtained than in the related art, thereby maximizing astigmatism correction by the quadrupole lens.

As described above, the electron gun for the color cathode ray tube according to the present invention adjusts the capacitance between the electrodes by adjusting the amplitude of the voltage not passing through the resistor and the amplitude (Spp) of the voltage passing through the resistor. It is possible to improve the filtering effect by more than%. In addition, by placing a conductor with a separate voltage in the area where the amplitude (Spp) of the voltage reduced through the resistor is applied, the filtering lowers the amplitude below 30% of the amplitude of the AC dynamic focus voltage not passing through the resistor. You can expect the effect.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it can be modified by those skilled in the art within the technical scope of the present invention. And the cathode ray tube device as described above is applicable to a monitor, a television receiver, and the like.

Claims (7)

A cathode structure including an electron emission source, and at least three or more focus electrodes and final acceleration electrodes arranged inline to form an electron lens for focusing and accelerating an electron beam emitted from the cathode structure, A voltage drop means for dropping an AC voltage in synchronization with a deflection signal and applying it to a focus electrode on the other side, and a constant voltage is applied to the focus electrode located at the center thereof. The method of claim 1, The voltage drop means is a gun for a color cathode ray tube, characterized in that the resistor installed inside or outside the neck portion of the cathode ray tube. And a plurality of focus electrodes and final acceleration electrodes arranged inline, forming a cathode, a control electrode and a screen electrode as electron emission sources constituting a triode, and an electron lens for focusing and accelerating the electron beam emitted from the cathode. Applying an AC dynamic focus voltage in synchronization with a deflection signal to at least one of the focus electrodes, And when the AC dynamic focus voltage is applied to at least one focus electrode by a voltage drop means, one is applied to a focus electrode adjacent to the screen electrode. The method of claim 3, The voltage drop means is a gun for a color cathode ray tube, characterized in that the resistor installed inside or outside the neck portion of the cathode ray tube. A cathode control electrode and a screen electrode forming a triode, first, second, third and fourth focus electrodes sequentially installed from the screen electrode, and a final acceleration electrode disposed adjacent to the fourth focus electrode, An AC dynamic focus voltage synchronized with a deflection signal is applied to the fourth focus electrode, and the AC dynamic focus is applied to the first and third focus electrodes adjacent to the screen electrode by being dropped by a voltage drop means. An electron gun for a color cathode ray tube, characterized in that a constant voltage is applied to the second focus electrode. The method of claim 5, Electron gun for color cathode ray tube, characterized in that the voltage applied to the second focus electrode is applied with the same voltage as the voltage applied to the screen electrode. The method of claim 5, The voltage drop means is a gun for a color cathode ray tube, characterized in that the resistor installed inside or outside the neck portion of the cathode ray tube.