JPH0443533A - cathode ray tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to cathode ray tubes such as color television picture tubes and color display tubes for terminal devices, and particularly to displaying high-resolution images over the entire screen. Related to cathode ray tubes capable of

[Prior Art] As a color television picture tube device, a single electron gun three-beam electron gun is known, which can realize low aberrations by increasing the diameter of its electron lens.

An example of this type of electron gun is the one disclosed in Japanese Patent Publication No. 49-5591.

FIG. 10 is a configuration diagram illustrating the electrode configuration of the single electron gun three-beam type electron gun described in the above-mentioned publication.

As shown in the figure, this electron gun has a common plane (x -z plane) cathodes 81.82.83 (K *, K G
, K m ) for the first electrode 1 (G+).

Second electrode 2 (G), third electrode 3 (G3), fourth electrode 4 (
G4), the fifth electrode 5 (C5) is arranged in common.

Here, cathodes 81, 82, 83 . A bipolar portion 13 is formed by the first electrode 1 and the second electrode 2, and a cylindrical third electrode 3. The fourth electrode 4 (focusing electrode) and the fifth electrode 5 form a unibond main electron lens (hereinafter simply referred to as main lens).

The three electron beams emitted from each cathode 81, 82, 83 are designed to intersect at a position that satisfies the Fraunhofer condition (condition for zero coma aberration) approximately at the center of the main lens.

Out of the three electron beams that have passed through the main lens, the outer beams (hereinafter referred to as side beams) are directed toward the central electron beam by electrostatic deflection plates 61 and 62 provided after the fifth electrode 5. The three electron beams are deflected and converge on the screen 10.

On the other hand, in order to optimally converge (hereinafter also referred to as concentration) the three electron beams even at the periphery of the screen, the horizontal deflection magnetic field distribution of the deflection yoke is given a binction shape, and the vertical deflection magnetic field distribution is given a barrel shape. I had it.

There is a so-called self-convergence deflection yoke.

However, a picture electrode magnetic field component is formed by the distortion of the magnetic field distribution of this self-convergence deflection yoke, and this quadrupole magnetic different component causes astigmatism in the electron beam. Hereinafter, this distortion will be referred to as quadrupole distortion.

FIG. 11 is an explanatory diagram of quadrupole-like distortion caused by the self-convergence deflection yoke.

As shown in the figure, due to the distortion of the magnetic field distribution of the self-convergence deflection yoke, the electron beam B is subjected to a focusing action in the vertical direction (y-axis direction) and a diverging action in the horizontal direction (x-axis direction). As a result, in the case of a circular beam spot at the center SC (the part where the deflection is zero) on the screen, the beam spot at the periphery of the screen is horizontal (horizontal direction:
The core CO becomes underfocused in the X-axis direction), causing lateral spread in the core CO, and becomes overfocused in the vertical direction, resulting in a vertically long overfocused part with its long axis in the vertical direction (vertical direction: y-axis direction). A halo HA occurs and the beam spot becomes substantially larger.

This causes deterioration of resolution in the peripheral portion of the screen.

On the other hand, in a single electron gun three-beam electron gun, a correction quadrupole is installed to cancel the quadrupole-like distortion caused by the self-convergence deflection yoke, and the cross section of the electron beam is made vertically long. A method of applying distortion is adopted.

FIG. 12 is an explanatory diagram of a correction means for quadrupole-like distortion caused by a self-convergence deflection yoke, in which 9 is a deflection yoke, 11 is a neck tube section of a cathode ray tube, 12 is an electromagnetic quadrupole coil, and 10th The same reference numerals as in the figure correspond to the same parts.

Further, FIG. 13 is an explanatory diagram of a quadrupole coil, which is a correction means for the quadrupole distortion shown in FIG. 12, and its generated magnetic field distribution.

As shown in FIG. 12, an electromagnetic quadrupole coil 12 is provided on the outer periphery of the neck tube section 11 of the cathode ray tube at a position corresponding to the main lens of the electron gun housed inside the neck tube section. This electromagnetic quadrupole coil 12 corrects quadrupole distortion caused by the self-convergence deflection yoke.

FIG. 13 shows the magnetic field distribution formed in the neck tube section 11 by the electromagnetic quadrupole coil 12, which has a quadrupole-like magnetic field distortion as indicated by the arrows in the figure.

The current flowing through this electromagnetic quadrupole coil 12 is
At the same time, a dynamic focus voltage synchronized with the deflection current applied to the deflection yoke is applied to the fourth electrode 4, which is a focusing electrode, so that the beam at the periphery of the screen by the self-convergence deflection yoke is applied. This corrects spot distortion.

Another means for correcting the beam spot distortion in the peripheral portion of the screen caused by the self-convergence deflection yoke is disclosed in Japanese Patent Laid-Open No. 64-65752.

FIG. 14 is an explanatory diagram of the cathode ray tube disclosed in the above publication, in which the fourth electrode 4 is arranged in three electrode portions 41, 42 in the direction of the tube axis 2.
．． A constant fixed focusing voltage is applied to the central electrode portion 42, and a dynamic focusing voltage is applied to the electrode portions 41 and 43 on both sides (at the front and back on both sides of the tube axis). Note that the same symbols as in FIG. 12 correspond to the same parts.

FIG. 15 is an explanatory diagram of the cross-sectional shape of the electron beam at the divided fourth electrode, in which (a) shows when the electron beam is at the scanning position at the center of the screen, and (b) shows when the electron beam is at the scanning position at the center of the screen. Indicates when it is in a peripheral scanning position.

With the configuration shown in FIG. 14, when the electron beam is at the scanning position at the center of the screen, the electrode portions 41, 42, 43
are at the same potential, and the three electrode parts 41, 42° 43
The electric field distribution on the X-2 plane formed by is rotationally symmetrical with respect to the tube axis 2, and as shown in FIG. becomes.

On the other hand, in scanning around the screen, the 15th
As shown in (b) of the figure, due to the influence of the electron beam passing aperture h4□ of the central electrode portion 42 and the narrow portions of the electron beam passing apertures h41 and h43 of the front and rear electrode portions 41 and 43, A quadrupole effect occurs in the electric field distribution, and a force that spreads in the y-axis direction and narrows in the x-axis direction acts on the electron beam B,
Its cross section has a vertically elongated shape.

In other words, a self-convergence ([iii) distortion rotated by 90 degrees with respect to the quadrupole distortion caused by the yoke is created by the electrostatic quadrupole electric field generated by the dynamic focus voltage, and the beam spot is automatically changed by the self-convergence deflection yoke magnetic field. This is to correct distortion.

[Problems to be Solved by the Invention] The device using an electromagnetic quadrupole magnetic field explained in the above-mentioned prior art requires (1) an electromagnetic quadrupole coil on the outer periphery of the neck, and its position must be accurately selected; (2) Since it is necessary to apply current to the electromagnetic quadrupole coil in synchronization with the deflection current for the self-convergence deflection yoke, a dedicated circuit is required for this purpose. (3) Power is required to energize the electromagnetic quadrupole coil, which increases the power consumption of the cathode ray tube.

In addition, in the case of using an electrostatic quadrupole, (4) assembly and manufacturing of the electron gun becomes complicated, as it is necessary to accurately align the axis of the electrode portions 4L42 and 43 of the fourth electrode 4 divided into three;
(5) During dynamic focusing, the electric field generated by the three-divided electrode portions 41, 42, and 43 causes the intersection position of the electron beam to deviate from the Franhofer condition, and this Franhofer condition does not perfectly match the center of the main lens. This caused problems such as coma aberration occurring and the beam spot not being able to be made circular.

An object of the present invention is to solve the problems of the above-mentioned prior art, to reliably avoid the occurrence of beam spot distortion due to magnetic field distortion of the self-convergence deflection yoke, and to obtain high resolution over the entire screen area. Our goal is to provide cathode ray tubes.

[Means for solving the problem] The above object is to provide electrostatic deflection means on the electron source side and the screen side of the main lens of the electron gun, and to divide the focusing electrode forming the main lens into two parts. This is achieved by providing an electrostatic quadrupole lens in the electrode section.

[Effect] The electrostatic quadrupole electric field generated by the electrostatic quadrupole lens is
It has the effect of correcting the horizontally elongated beam spot at the periphery of the screen described in FIG. 11 to a vertically elongated beam spot.

In other words, the beam spot at the periphery of the screen has a circular shape with distortion caused by the self-convergence deflection yoke corrected.

On the other hand, due to the action of the electrostatic quadrupole lens, the orbits of the side beams on both sides are deflected, and the three electron beams become under-focused (unfocused). The deflection action of the electric deflection means is weakened so that proper concentration can be obtained.

Therefore, the three electron beams are properly concentrated over the entire surface of the screen.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram illustrating the electrode configuration of an electron gun of a cathode ray tube according to the present invention, in which (a) is a cross-sectional view on the x-z plane;
(b) is a cross-sectional view on the y-Z plane.

In the figure, 1 is the first electrode (G1), 2 is the second electrode (G1), and 2 is the second electrode (G1).
G2), 3 is the third electrode (G,), 13 is the triode part, 4 is the fourth electrode (G4), 31, 32 . and 321.322 are electrode parts obtained by dividing the third electrode, 50.60 is the electron beam trajectory, 61.62 is the second electrostatic deflection means, n, '12 is the first electrostatic deflection means, 81.82 .83 is a cathode (Km, Kg, Km) arranged in the X-axis direction corresponding to red, green, and blue and installed parallel to the two axes (tube axis).

Then, the cathodes 81, 82, 83, the first electrode 1 and the second
A triode portion 13 is formed with the electrode 2 .

First electrode 1. Second electrode2. Third electrode 3 and fourth electrode 4
are arranged in common with the cathodes 81, 82, 83, and the third electrode 3 and fourth electrode 4 form a bipotential main lens.

The third electrode 3 is divided into electrode parts 31 and 32, between which a first electrostatic deflection means 71.72 is arranged.
will be provided. The electrode portion 32 of the third electrode 3 is further divided into a first electrode portion 321 and a second electrode portion 322.

The center beam B6 and the side beams BR and Bl that have traveled in parallel through the triode section 13 pass through the center of the main lens and travel in a diverging manner toward the screen.

A second electrostatic deflection means 61 is provided on the screen side of the main lens.
62 is arranged, and the side beams 8 and Bm passing through the main lens are converged on the screen. Although the second electrostatic deflection means 61 and 62 are shown as plate-shaped bodies, this is an electrostatic deflection acting surface portion and is not limited to a plate-shaped body.

Now, a constant fixed focusing voltage ■ is applied to the first electrode portion 321 and the electrode portion 31 of the divided third electrode 3, and a dynamic focusing voltage V□, which will be described later, is applied to the second electrode portion 322. .

Like the second electrostatic deflection means, the first electrostatic deflection means is not limited to the plate-like body shown in the drawings. Hereinafter, for convenience of explanation, it will be referred to as a deflection plate.

Now, the voltage of the deflection plate 71 on the outside with respect to the tube axis is ■. Then, VC=Vfd.

The voltage of the fourth electrode 4 is VG4, the voltage of the deflection plate 61 is Vl,
When the voltage of the deflection plate 72 is VD and the voltage of the deflection plate 62 is 2, VG4=VB, VA<Vll, and Vc<V.

For example, the cutoff voltage of the cathode is about 70V, a video signal is added to this, the voltage of the first electrode 1 is set to the ground potential, the voltage of the second electrode 2 is set to about 600V, and the voltage of the first electrode 321 is set to about 600V.
and a fixed focusing voltage (■) applied to one electrode 31 of the third electrode 3, approximately 8 kV, (■). approximately 9°5kV, VG-(=V1
1) is approximately 27 kV, and Approximately 8 kV (-V,).

Further, an example of the electrode dimensions of the electron gun in the example is shown below.

Here, the electrode inner diameter d is standardized, and the length of the electrode 31 is 2.
．． 65 d, and the lengths of the deflection plates 71 and 72 are both 0.7 d.
.

The length of the electrode 32 is 1. Od, the lengths of the first electrode portion 321 and the second electrode portion 322 are both 0.42d, and the length of the fourth electrode portion 321 is 0.42d.
The length of electrode 4 is 2. Od, the axial length of the deflection plates 61.62 is both 1.8d, the length from the cathode side end of the electrode 31 to the screen side end of the deflection plate 61.62 is 8.75d,
The distance from the cathode end of the electrode 31 to the screen is 3
6.4d, and the distance between the deflection plates 61, 62 and 71.72 is 0.35d in the X direction.

Also, side beams B*, Bm and center beam B6
The emission interval is 0.35d in the X-axis direction.

FIG. 2 is a structural diagram of the surface of the second electrode portion of the third electrode that faces the first electrode portion, and the surface of the second electrode portion 322 that faces the first electrode portion 321 includes:
It has a rectangular opening E that is wide in the X-axis direction and narrow in the X direction and the X direction perpendicular to the two directions.

FIG. 3 is a waveform diagram of the dynamic focus voltage Vta.
A waveform in which parabolic voltages shown by curve 4 having one horizontal scanning period are superimposed is selected.

In other words, when the electron beam is at the scanning position at the center of the screen, the first electrode part 321 and the second electrode part 322 of the third electrode are at the same voltage, and the voltage formed by these two electrode parts 321 and 322 is The electric field distribution in the x-z cross section becomes rotationally symmetrical with respect to the tube axis 2.

FIG. 4 is an explanatory diagram of the action of the electrostatic quadrupole electric field according to the present invention. When the electron beam is at the scanning position at the center of the screen, three beams are emitted as shown in FIG. 4(a). The cross-sectional shape of the electron beam is circular, but in the periphery of the screen, as shown in FIG. Due to the influence of , a quadrupole effect occurs in the electric field distribution, and a force that spreads in the X direction and narrows in the X direction acts on the electron beam, and the beam spot becomes vertically elongated.

Therefore, the beam spot at the periphery of the screen described above with reference to FIG. 11 becomes circular because the distortion caused by the self-convergence magnetic field is canceled out.

Furthermore, since a dynamic focus voltage is applied to the second electrode portion 322 and the peripheral portion of the screen is also in focus, the circular spot can be made smaller.

Next, the concentration of the three electron beams will be explained by returning to FIG. 1.

Here, for ease of understanding, the voltage applied to the deflection plate 71 will be explained as a fixed focusing voltage (2).

In FIG. 1, the trajectory of the side beam is as indicated by the dotted line 50 due to the lensing action of the dynamic focus voltage of the second electrode portion 322.

That is, due to the effect of the self-convergence magnetic field, the three electron beams become underfocused (unfocused) in the peripheral area of the screen.

Therefore, in this embodiment, the underfocus is corrected by applying a dynamic focus voltage Vfd to the deflection plate 71 and a fixed voltage V to the deflection vi72.

That is, when the deflection yoke is not performing deflection, the voltage of the deflection plate 71 is . The voltage ■ gradually increases, so the trajectory of the side beam follows the dashed line 6
It changes as shown by 0, and the three electron beams come to be properly concentrated.

Of course, a fixed focusing voltage ■, is applied to the deflection plate 71, and a voltage ■, 4゛ is applied to the deflection plate 72 on the tube axis Z side, which gradually decreases as the deflection angle increases in synchronization with the dynamic focus voltage. By doing so, proper concentration can be achieved over the entire screen.

Furthermore, a fixed voltage (4) is applied to the deflection plate 72, and the deflection plate 7
1 may be applied with a voltage v,,,' that gradually increases as the deflection angle increases in synchronization with the dynamic focus voltage Vta, or alternatively, a voltage v,,,' that gradually increases as the deflection angle increases may be applied to the deflection plate 71 and the deflection plate 72 in synchronization with the dynamic focus voltage Vta. Deflection plate 7
The same effect as described above can be obtained by applying relatively changing voltages such that 1 is high and the deflection plate 72 is low.

In the case of supplying a plurality of dynamic focus voltages as described above, it is also possible to obtain a dynamic focus voltage of a predetermined magnitude from a single power supply using appropriate resistance dividing means. The same applies to other fixed voltages.

FIGS. 5 to 9 are explanatory diagrams of other embodiments of the present invention.

Figure 5 shows the first electrode which is further divided into two parts of the third electrode 3 which is divided into two parts.
FIG. 3 is a front view showing the configuration of a surface facing an electrode portion 321 and a second electrode portion 322;

In the embodiment described above, a circular opening was formed in the opposing surface of the first electrode part 321 facing the second electrode part 322, whereas in this embodiment, the opening was wide in the y-axis direction and
Three rectangular apertures F having a narrow width in the axial direction are provided corresponding to each of the three electron beams.

This allows the effect of the electrostatic quadrupole to be more emphasized.

Similar to FIG. 5, FIG. 6 shows the first electrode portion 321 and the second electrode portion 321.
6 is a front view showing the configuration of a surface facing the electrode portion 322 of FIG. One rectangular opening F' is provided, and the same effect as the configuration shown in FIG. 5 is achieved.

7, 8, and 9 show the first electrode portion 322 of the second electrode portion 322.
This figure shows other examples of the shape of the surface facing the electrode portion 321, all of which have shapes that generate an electrostatic image electrode electric field.

In FIG. 7, the electron beam passing aperture of the second electrode portion 322 has a horizontally long rectangular shape corresponding to each electron beam.

FIG. 8 shows the first electrode portion 321 of the second electrode portion 322.
A rectangular opening E shown in FIG.
In addition, in FIG. 9, a second electrode part 322 is provided with three circular openings Q in a part facing the first electrode part 321. , horizontal plates H' are provided that sandwich the circular opening Q from above and below in the y-axis direction.

These horizontal plates H, H' have the effect of emphasizing the action of the electrostatic quadrupole.

An electrostatic quadrupole electric field can also be effectively generated by appropriately combining the electrode shapes of the embodiment described above and the other embodiments shown in FIGS. 5 to 9.

[Effects of the Invention] As explained above, according to the present invention, distortion of the electron beam can be eliminated over the entire surface of the screen, and three electron beams can be appropriately concentrated on the screen, which is different from the conventional method. It is possible to provide a cathode ray tube with excellent functionality, excluding the technical drawbacks.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the electrode configuration of an electron gun for a cathode ray tube according to the present invention, FIG. 3 is a waveform diagram of the dynamic focus voltage V (4), FIG. 4 is an explanatory diagram of the action of the electrostatic quadrupole electric field according to the present invention, and FIG.
Figures 6 and 7. 8 and 9 are explanatory diagrams of other embodiments of the present invention, FIG. 10 is a schematic diagram illustrating the electrode configuration of a single electron gun three-beam electron gun according to the prior art, and FIG. 11 is a self-convergence deflection Explanatory diagram of quadrupole distortion due to yoke, 1st
Figure 2 is a schematic diagram illustrating the means for correcting the quadrupole distortion caused by the self-convergence deflection yoke, and Figure 13 shows the quadrupole coil and the means for correcting the quadrupole distortion shown in Figure 12. FIG. 14 is a schematic diagram illustrating the configuration of a cathode ray tube according to the prior art, and FIG. 15 is a diagram illustrating the cross-sectional shape of the electron beam at the divided fourth electrode. 1...First electrode (GO12...Second electrode (Gz
), 3...Third electrode (G,), 13...Triode part, 4...Fourth electrode (G4), 31.32,321
, 322 ... Electrode part obtained by dividing the third electrode,
50°60 ・・・Electron beam orbit, 61.62 ・
... Second electrostatic deflection means, 71.72 ... First electrostatic deflection means, 81.82.83 ... Cathode.

Claims (1)

[Claims] 1. x-z including a tube axis z and an axis x orthogonal to the tube axis z;
an electron source that generates multiple electron beams arranged on a plane;
A triode section that controls the emission of electron beams from the electron source, a focusing electrode that commonly focuses multiple electron beams emitted from the triode section, and an acceleration electrode that accelerates the focused electron beams are connected to a common tube axis z. A main electron lens is arranged sequentially on this tube axis z as an axis, and a first electron lens is arranged on the electron source side of the main electron lens.
A cathode ray comprising an electron gun consisting of an electrostatic deflection means and a second electrostatic deflection means arranged on the screen side of the main electron lens, and a magnetic deflection yoke for scanning a plurality of electron beams on the screen. In the tube, the focusing electrode is composed of a first electrode portion and a second electrode portion that are divided and arranged in order from the electron source side with respect to the tube axis z direction and form a non-axisymmetric lens in opposing parts. A cathode ray tube, characterized in that a voltage varying in synchronization with scanning of the plurality of electron beams is applied to the second electrode portion. 2. A cathode ray tube according to claim 1, further comprising means for changing the deflection strength of said first electrostatic deflection means in synchronization with scanning of said plurality of electron beams. 3. In claim 2, the first electrostatic deflection means has a plurality of electrostatic deflection working surfaces arranged so as to sandwich the electron beam between the x-z planes, and arranged outside with respect to the tube axis. A cathode ray tube, further comprising means for applying a voltage that changes in synchronization with scanning of the plurality of electron beams to the electrostatic deflection surface. 4. The cathode ray tube according to claim 1, wherein the main electron lens is a bipotential electron lens.