JPH0636705A - Color picture tube - Google Patents

Abstract

PURPOSE:To provide good resolution on the whole screen by forming an auxiliary lens section with three electrodes forming a unipotential electronic lens and an electrode forming an asymmetrical lens. CONSTITUTION:The main lens section of an electron gun 25 is constituted of a focusing electrode G5 applied with the dynamic focus voltage, intermediate electrodes Gm1, Gm2, and a final accelerating electrode G6 to form an asymmetrical lens. An auxiliary lens section is constituted of electrodes G3, G4, G5 forming a unipotential electronic lens and an electrode Gs forming an asymmetrical lens. The AC voltage component of the dynamic focus voltage applied to G5 is also induced to Gs, and the change of the lens action of the asymmetrical lens of the main lens section can be compensated by the change of the lens action of the asymmetrical lens of the auxiliary lens section. The resolution is improved on the whole screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube, and more particularly to a color picture tube provided with an electron gun for improving resolution and uniforming focus quality.

[0002]

2. Description of the Related Art Generally, a color picture tube deflects a three-electron beam emitted from an electron gun by a magnetic field generated by a deflection yoke mounted on the outside of an envelope, and selects the three-electron beam by a shadow mask. The phosphor screen is horizontally and vertically scanned to form a color image on the phosphor screen.

In such a color picture tube, in particular, the electron gun is an in-line type electron gun which emits three electron beams arranged in a line consisting of a center beam passing through the same horizontal plane and a pair of side beams. (A)
Pincushion type horizontal deflection magnetic field 1H shown in (b)
In combination with a deflection yoke that generates an inhomogeneous uniform magnetic field consisting of a barrel-shaped deflection magnetic field of 1 V shown in Fig. 1, a self-convergence in-line type color picture tube that self-focuses the three electron beams arranged in a row is now a general-purpose color picture tube. Has become the mainstream.

In FIGS. 10A and 10B, 2G is a center beam, and 2B and 2R are a pair of side beams.

However, this self-convergence in-line type color picture tube has a problem that the cross-sectional shape of the electron beam is distorted (deflection distortion) as the deflection angle increases, and the resolution at the peripheral portion of the screen deteriorates. That is, FIG.
As shown in, the beam spot 4a at the center of the screen 3 is
The beam spot 4b in the peripheral part of the screen 3 produces an elliptical high-brightness core part 5 which is long in the horizontal direction, and a low-brightness halo part 6 extending in the vertical direction, although it can be made almost a perfect circle. , The resolution at the periphery of screen 3 is severely degraded.
Due to the inhomogeneity of the deflection magnetic field, the distortion of the beam spot at the periphery of the screen 3 causes horizontal focusing as shown by 2R ′ for the side beam 2R in FIGS. 10 (a) and 10 (b). Is weakened and vertical focusing is strengthened.

[0006] As one of means for improving the deterioration of resolution due to the above-mentioned deflection distortion, Japanese Patent Laid-Open No. 64-38 related to the present inventors.
Japanese Patent No. 947 discloses the electron gun shown in FIG. This electron gun consists of three cathodes KB, KG,
KR, first to sixth electrodes G1 to G6 of integral structure sequentially arranged on the cathodes KB, KG, and KR, and two intermediate electrodes between the fifth electrode G5 and the sixth electrode G6. It has a structure in which Gm1 and Gm2 are arranged.

In this electron gun, the main lens portion that focuses the three electron beams toward the phosphor screen is the fifth electrode G5 as the focusing electrode, the two intermediate electrodes Gm1 and Gm2, and the sixth accelerating electrode as the final accelerating electrode. The high voltage supplied to the final accelerating electrode is divided into a predetermined voltage by a resistor 8 arranged along the electron gun, and the two intermediate electrodes Gm1 and Gm2 are composed of an electrode G6. , A dynamic focus voltage V in which a constant DC voltage is superimposed on an AC voltage component that changes in a parabolic shape in synchronization with the deflection of the deflection yoke.
D (focusing voltage) is supplied.

With such a structure, the main lens portion of the electron gun is provided with a fifth electrode G5 and an intermediate electrode Gm1 adjacent to the fifth electrode G5 for strongly focusing the electron beam in the vertical direction. 1 quadrupole lens is formed and the intermediate electrode Gm
2 and the sixth electrode G6 adjacent to this intermediate electrode Gm2,
A second quadrupole lens is formed that causes the electron beam to diverge strongly in the vertical direction. The first and second quadrupole lenses are in equilibrium when the electron beam is directed to the center of the screen, and a substantially circular beam spot is obtained at the center of the screen. On the other hand, when it is deflected to the peripheral part of the screen, the focusing voltage of the fifth electrode G5 rises and the fifth electrode G5 and the intermediate electrode
Since the potential difference from Gm1 becomes small, the first quadrupole lens becomes weak, and the electron beam is relatively strongly affected by the second quadrupole lens. This offsets the deflection distortion that is strongly focused in the vertical direction.

However, if a focusing voltage in which a parabolic AC voltage component is superimposed on a constant DC voltage is applied to the fifth electrode G5 as described above, the fifth electrode G5 and the intermediate electrode adjacent to the fifth electrode G5 are applied.
Capacitance exists between the intermediate electrode Gm1 and the intermediate electrode Gm2 and between the intermediate electrode Gm2 and the sixth electrode G6 adjacent to the intermediate electrode Gm1. Among them, the parabolic AC voltage component is induced to the intermediate electrodes Gm1, Gm2 via this electrostatic capacitance, and the intermediate electrodes Gm1, Gm2
Potential changes in synchronization with the deflection of the deflection yoke.

However, originally, this electron gun has an intermediate electrode Gm1.
, Gm2 constant and the first quadrupole lens and the second
Since it is designed to be balanced with the quadrupole lens, the first quadrupole lens and the second quadrupole lens lose their balance when the potentials of the intermediate electrodes Gm1 and Gm2 change as described above, and the screen The beam spot at the center becomes distorted.

FIG. 13 is a view for explaining the above phenomenon, and is the fifth electrode G5 which is the focusing electrode shown in FIG. 13 (a).
A DC voltage of about 28% of the high voltage applied to the sixth electrode G6, which is the final acceleration electrode, a DC voltage of about 40% to the intermediate electrode Gm1, and a DC voltage of about 65% to the intermediate electrode Gm2. If an AC voltage component that changes in a parabolic shape in synchronization with the deflection of the deflection yoke is superimposed on the fifth electrode G5, for example, if the electrostatic capacitances 10 between the electrodes are the same, then it is superimposed on the fifth electrode G5. 2 / of the parabolic AC voltage component
3 is guided to the intermediate electrode Gm1 and 1/3 is guided to the intermediate electrode Gm2. The solid lines 11a to 11 shown in FIG.
When d is a predetermined value, it changes as shown by broken lines 12a to 12c. That is, the focusing voltage (solid line 11a) decreases at the center of the screen as shown by the broken line 12a. However, the decrease of the focusing voltage at the center of the screen can be adjusted to a predetermined value by the DC component shown by the solid line 13. In contrast, the intermediate electrode
The potentials of Gm1 and Gm2 also fall below a predetermined value at the center of the screen, as indicated by the broken lines 12b and 12c, respectively. However, the potentials of the intermediate electrodes Gm1 and Gm2 cannot be adjusted. As a result, at the center of the screen, the first quadrupole lens becomes weak, while the second quadrupole lens becomes strong. Therefore, as shown in FIG. 14, the beam spot 4a in the central portion of the screen is distorted, and the resolution in the central portion of the screen deteriorates. On the other hand, in the peripheral portion of the screen, the potentials of the intermediate electrodes Gm1 and Gm2 both rise, so that the first quadrupole lens becomes stronger than the design value and the second quadrupole lens becomes weaker. As a result, the beam spot around the screen is also distorted, and the resolution is not sufficiently improved.

[0012]

As described above, the three electron beams emitted from the electron gun and arranged in a row passing through the same horizontal plane are made into a non-uniform structure in which the horizontal deflection magnetic field is a pincushion type and the vertical deflection magnetic field is a barrel type. The self-convergence in-line color picture tube that deflects by the magnetic field of the deflection yoke that generates a magnetic field has a problem that the cross-sectional shape of the electron beam is distorted as the deflection angle increases, and the resolution at the peripheral portion of the screen deteriorates.

As a means for improving the deterioration of the resolution due to the deflection distortion, two intermediate electrodes are arranged between the focusing electrode and the final accelerating electrode forming the main lens portion of the electron gun, and the intermediate electrodes are The high voltage supplied to the final acceleration electrode is divided by a resistor to supply a predetermined voltage, and a constant DC voltage is superimposed on the focusing electrode with an AC voltage component that changes in a parabolic shape in synchronization with the deflection of the deflection yoke. There is a color picture tube adapted to supply such a dynamic focus voltage.

However, even if the electron gun is constructed as described above, the parabolic AC voltage component of the voltage applied to the focusing electrodes is a capacitance that is present between the electrodes forming the main lens portion. Is induced by the two intermediate electrodes via the, and the potential of each intermediate electrode changes in synchronization with the deflection of the deflection yoke, so that not only the beam spot in the central portion of the screen is distorted but also the beam in the peripheral portion of the screen is distorted. There is a problem that the spot is also distorted and the resolution is not sufficiently improved.

The present invention has been made to solve the above problems, and an object of the present invention is to construct a color picture tube in which a good resolution can be obtained in the central portion and the peripheral portion of the screen.

[0016]

An auxiliary lens unit for prefocusing an electron beam emitted from an electron beam generating unit and a main lens unit for focusing an electron beam prefocused by the auxiliary lens unit on a phosphor screen. The main lens portion of which includes a focusing electrode to which a dynamic focus voltage is applied, which is sequentially arranged in the phosphor screen direction from the electron beam generating portion side, one or more intermediate electrodes, and a final accelerating electrode. In a color picture tube including an electron gun in which at least one asymmetric lens is formed by, the auxiliary lens portion is connected to three electrodes forming a unipotential type electron lens and one of the intermediate electrodes. The auxiliary lens portion is composed of one electrode forming at least one asymmetric lens.

[0017]

As described above, the auxiliary lens portion for prefocusing the electron beam is connected to the three electrodes forming the unipotential type electron lens and one of the intermediate electrodes forming the main lens portion. When the auxiliary lens unit is composed of one electrode forming at least one asymmetric lens, when the AC voltage component of the dynamic focus voltage applied to the focusing electrode is guided to the intermediate electrode forming the main lens unit, The AC voltage component of the dynamic focus voltage is also induced to one electrode forming the asymmetrical lens of the auxiliary lens unit to assist the change of the lens action of the asymmetrical lens of the main lens unit caused by the induction of the AC voltage component of the dynamic focus voltage. This can be compensated by a change in the lens action of the asymmetric lens of the lens unit.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 3 shows a color picture tube which is one of the embodiments. This color picture tube consists of panel 20 and this panel
A phosphor screen 22 having a three-color phosphor layer that emits blue, green, and red is formed on the inner surface of the panel 20 that has an envelope composed of a funnel 21 integrally joined to 20. A shadow mask 23 having a large number of electron beam passage holes formed therein is arranged so as to face the screen 22. On the other hand, in the neck 24 of the funnel 21, a center beam 2G and a pair of side beams 2 that pass on the same horizontal plane.
The following in-line type electron gun 25 which emits three electron beams 2B, 2G and 2R arranged in a line consisting of B and 2R, and this electron gun 25
A resistor for supplying a predetermined voltage to a predetermined electrode is disposed along the electron gun 25. Further, an internal conductive film 26 is formed by coating from the inner surface of the large-diameter portion of the funnel 21 to the inner surface of the adjacent portion of the neck 24.

Then, the three electron beams 2B, 2G, 2R emitted from the electron gun 25 are generated as an inhomogeneous uniform magnetic field composed of a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field mounted outside the funnel 21. The fluorescent screen 22 is deflected by the deflecting yoke 28 and is horizontally and vertically scanned through the shadow mask 23 so that a color image is displayed on the fluorescent screen 22.

As shown in FIG. 1, the electron gun 25 includes three cathodes KB, KG, KR arranged in a row in the horizontal direction, and three cathodes KB, KG, KR for heating the three cathodes separately. Heater (not shown), first, second, and third electrodes G sequentially arranged in the phosphor screen direction from the cathodes KB, KG, and KR.
1, G2, G3, 4th, 5th electrodes G4, G5, 2 intermediate electrodes Gm1
, Gm2, a sixth electrode G6, and a shield cup C attached to the sixth electrode G6, and in this electron gun 25, an auxiliary electrode Gs is provided between the third electrode G3 and the fourth electrode G4. It is arranged. And each electrode G1, G2, G3, G excluding its cathodes KB, KG, KR, heater and shield cup C
s, G4, G5, Gm1, Gm2, and G6 are integrally fixed by a pair of insulating supports (not shown).

The respective electrodes of the electron gun 25 are formed in an integral structure, and the first and second electrodes G1 and G2 thereof are plate electrodes having a relatively thin plate thickness, and these electrodes are arranged in a row. Corresponding to the three cathodes KB, KG, and KR, three small circular openings are provided. 3rd grid G3 is 2
It consists of a cylindrical electrode with the open sides of the cup-shaped electrodes butted together, and on the side of the second electrode G2, there are three circular apertures, which are slightly larger than the apertures of the second electrode G2, arranged in a row. The cathode K
B, KG, KR are provided, and on the auxiliary electrode Gs side, as shown in FIG. 2, three vertically elongated openings each having a major axis in the vertical direction larger than the opening on the second electrode G2 side. Holes 30 are provided corresponding to the three cathodes KB, KG, KR arranged in a line.

Each of the auxiliary electrode Gs and the fourth electrode G4 is composed of a tubular electrode in which the opening sides of two cup-shaped electrodes are butted against each other. The auxiliary electrode Gs and the fourth electrode G4 have a third electrode G3, respectively. Three circular openings larger than the openings on the second electrode G2 side are provided corresponding to the three cathodes KB, KG, KR arranged in a line.

The fifth electrode G5 is composed of a pair of cylindrical electrodes formed by abutting the opening sides of two cup-shaped electrodes.
On the fourth electrode G4 side of G5, three vertically elongated holes having the same size as the hole 30 on the auxiliary electrode Gs side of the third electrode G3 shown in FIG. Cathode KB, KG, KR
On the side of the intermediate electrode Gm1, three circular or non-circular apertures of approximately the same size as the apertures of the fourth grid G4 are arranged in a row in the three cathodes KB, KG, KR. It is provided corresponding to.

Each of the intermediate electrodes Gm1 and Gm2 is composed of a plate electrode having a relatively large plate thickness, and these electrodes have three circular openings corresponding to the three cathodes KB, KG and KR arranged in a row. Is provided. The sixth electrode G6 is composed of a tubular electrode formed by abutting the opening sides of two cup-shaped electrodes.
On the side of the intermediate electrode Gm2 of the electrode G6, there are provided three circular or non-circular openings corresponding to the three cathodes KB, KG, KR arranged in a row, and on the shield cup C side, there is a row of arranged rows. Three circular holes are provided corresponding to the three cathodes KB, KG, and KR. Also, on the bottom of the shield cup C, three circular openings of the same size as the openings on the shield cup C side of the sixth electrode G6 are provided corresponding to the three cathodes KB, KG, KR arranged in a row. Has been.

Regarding the openings of the intermediate electrode Gm2 and the sixth electrode G6 on the side of the intermediate electrode Gm2, the central openings are coaxial with the central openings of the other electrodes, but the openings on both sides are , Are displaced outward in the arrangement direction (horizontal direction) of the openings with respect to the openings on both sides of the other electrodes.

The resistor 8 is attached along the back surface of the insulating support for integrally fixing the electrodes of the electron gun 25, and the terminal 32 provided at one end thereof is connected to the sixth electrode G6.
A terminal 33 provided at the other end is grounded directly or via a variable resistor 36 via a stem lead 35 (see FIG. 2) that hermetically penetrates the stem 34. The terminals 37 and 38 provided in the intermediate portion are connected to the intermediate electrodes Gm1 and Gm2, respectively.

The following voltages are applied to the electrodes of the electron gun 25 during operation. That is, a voltage in which a video signal is superimposed on a DC voltage of 180V is applied to the cathodes KB, KG, and KR, the first electrode G1 is grounded, and the second electrode G2 and the fourth electrode G4 are connected.
The electrode G4 is connected in the tube and a voltage of about 800 V is connected, and the third electrode G3 and the fifth electrode G5 are connected in the tube in the same manner and the voltage is about 8 to
A dynamic focus voltage VD, in which an AC voltage component that changes in a parabolic shape in synchronization with the deflection of the deflection yoke is superimposed on the DC voltage of 9 kV, is applied. Also, about 30 kV is applied to the sixth electrode G6 via an anode terminal, an internal conductive film, a valve spacer (not shown) attached to the shield cup C, etc.
Is applied to the intermediate electrode Gm1 in the tube, and the anode high voltage (about 30 kV) applied to the sixth electrode G6 is divided by the resistor 8 to
%, And a voltage of about 60% is applied to the intermediate electrode Gm2.

By applying such a voltage, each cathode is
The electron beams emitted from KB, KG, and KR diverge after forming a crossover in the vicinity of the first and second electrodes G1 and G2, and a prefocus lens formed by the second and third electrodes G2 and G3. Received pre-focusing by the third electrode G
3, pre-focused by the auxiliary lens portion formed by the auxiliary electrode Gs and the fourth and fifth electrodes G4, G5, and then by the main lens portion formed between the fifth electrode G5 and the sixth electrode G6, Finally it is focused on the phosphor screen.

In this case, the first lens G5 serving as a focusing electrode and the intermediate electrode Gm1 adjacent to the fifth electrode G5 strongly focus the three electron beams mainly in the vertical direction on the main lens portion. The quadrupole lens, and the intermediate electrode Gm2 and the sixth accelerating electrode G6 form a second quadrupole lens that strongly diverges the three electron beams mainly in the vertical direction.

In the auxiliary lens part, the auxiliary electrode Gs is arranged between the third electrode G3 and the fourth electrode G4 of the third, fourth and fifth electrodes G3, G4 and G5 which form a unipotential electron lens. As a result, the third quadrupole lens that strongly focuses the three electron beams mainly in the horizontal direction is provided between the third electrode G3 and the auxiliary electrode Gs, and the third quadrupole lens is provided between the fourth electrode G4 and the fifth electrode G5. A fourth quadrupole lens is formed that strongly diverges the electron beam mainly in the horizontal direction.

In the first and second quadrupole lenses of the main lens portion, the plate thicknesses of the opening portion of the fifth electrode G5 on the side of the intermediate electrode Gm1 and the opening portion of the sixth electrode G6 on the side of the intermediate electrode Gm2 are set. By making the thickness as thin as 1.0 mm or less, the radius of curvature of the lens in the horizontal direction is increased, and the lens strength in the horizontal direction is made relatively weaker than that in the vertical direction.
Further, in the third and fourth quadrupole lenses of the auxiliary lens portion, as shown in FIG. 2, the opening of the third grid G3 on the auxiliary electrode Gs side and the opening of the fifth electrode G5 on the fourth electrode G4 side are shown. It is formed by vertically increasing the lens strength in the horizontal direction relative to that in the vertical direction.

By the way, as described above, the fifth lens of the main lens portion is
The first quadrupole lens which strongly focuses the three electron beams mainly in the vertical direction by the electrode G5 and the intermediate electrode Gm1, and strongly diverges the three electron beams mainly in the vertical direction by the intermediate electrode Gm2 and the sixth electrode grid G6. In the electron gun 25 in which the second quadrupole lens is formed, the auxiliary electrode Gs is arranged between the third electrode G3 and the fourth electrode G4 of the auxiliary lens section, and the third electrode G3 and the auxiliary electrode Gs are A third quadrupole lens that focuses the three electron beams mainly in the horizontal direction is formed between the fourth electrode G4 and the fifth electrode G5 that strongly diverges the three electron beams mainly in the horizontal direction between the fourth electrode G4 and the fifth electrode G5. With the structure for forming the quadrupole lens, the following operational effects can be obtained.

That is, as shown by an AC equivalent circuit in FIG. 4, a DC voltage of 8 to 9 kV is applied to the fifth electrode G5, which is a focusing electrode, of an AC voltage component that changes in a parabolic shape in synchronization with the deflection of the deflection yoke. Dynamic focus voltage V superimposed
When D is applied, the AC voltage component is induced in the intermediate electrodes Gm1 and Gm2 via the electrostatic capacitance 10 between the electrodes as explained in the conventional electron gun, and some of that voltage is applied to the DC voltage. It is superimposed on the existing intermediate electrodes Gm1 and Gm2. As a result, the same AC voltage component as that of the intermediate electrode Gm1 is also superimposed on the auxiliary electrode Gs connected to the intermediate electrode Gm1. In this case, since the auxiliary electrode Gs faces the third electrode G3 connected to the fifth electrode G5, the electrostatic capacitance 10 also exists between the third electrode G3 and the auxiliary electrode Gs, The AC voltage component superimposed on the electrode Gm1 and the auxiliary electrode Gs becomes larger than that in the conventional electron gun shown in FIG. 9, and the intermediate focus electrode Gm1 and the auxiliary electrode Gs have a dynamic focus voltage VD of 4 /
5. A voltage of 2/5 is superimposed on the intermediate electrode Gm2. In this case, the voltage 40 superimposed on these two intermediate electrodes Gm1 and Gm2 and the auxiliary electrode Gs is, as shown in FIG. 5, higher than the voltage 41 originally applied to that electrode in the portion corresponding to the center of the screen. It becomes low and becomes high in the part corresponding to the peripheral part of the screen.

As a result, regarding the beam spot at the center of the screen, in the main lens portion, the voltages of the intermediate electrodes Gm1 and Gm2 become lower than the original voltage, respectively, and three electrons formed by the fifth electrode G5 and the intermediate electrode Gm1 are formed. The focusing action of the first quadrupole lens for vertically focusing the beam is weakened. In addition, the diverging action of the second quadrupole lens that vertically diverges the three electron beams formed by the intermediate electrode Gm2 and the sixth electrode G6 becomes strong, and the main lens unit as a whole is displayed as shown in FIG. The beam spot 4a in the central portion is changed to be vertically long. On the other hand, in the auxiliary lens section, the auxiliary electrode Gs
Voltage becomes lower than the original voltage, and the focusing action of the third quadrupole lens for vertically focusing the three electron beams formed by the third electrode G3 and the auxiliary electrode Gs is weakened, but the fourth
The diverging action of the fourth quadrupole lens that vertically diverges the three electron beams formed by the electrode G4 and the fifth electrode G5 is
Since the potential difference between the two grids G4 and G5 does not change, it does not change, and the beam spot 4a at the center of the screen changes horizontally as shown in FIG. 6 for the entire auxiliary lens unit.

Therefore, in the electron gun 25 as a whole, the beam spot in the central portion of the screen is corrected by the action of changing the beam spot in the central portion of the screen by the main lens portion into a vertically long tendency. hand,
It is possible to prevent the distortion of the beam spot at the center of the screen, which is caused by the dynamic focus voltage applied to the fifth electrode G5 being induced to the intermediate electrodes Gm1 and Gm2. For the beam spot around the screen, use the intermediate electrode.
The voltage of Gm1 and Gm2 rises higher than the original voltage, the action of the main lens part and the auxiliary lens part is opposite to the case of the center part of the above screen, and the change of the shape of the beam spot by the main lens part causes the effect of the auxiliary lens part. It is also possible to prevent the distortion of the beam spot in the peripheral portion of the screen. as a result,
The resolution can be improved over the entire screen.

Next, another embodiment will be described.

In the above embodiment, in order to form the third and fourth quadrupole lenses in the auxiliary lens portion, the openings on the fourth electrode side of the third electrode and the fourth electrode side of the fifth electrode are made vertically long. However, as a structure for forming the third and fourth quadrupole lenses in this auxiliary lens portion, a structure having a strong lens action in the horizontal direction may be used. For example, as shown in FIG. The fourth electrode side of electrode G3 and the fourth electrode of fifth electrode G5
Alternatively, each of the three openings 30 on the electrode side may be formed in a circular shape, and the projections 43 sandwiching the openings 32 from the arrangement direction of the openings 30 may be formed. Further, as shown in FIG. 8, a concave groove 44 may be formed instead of the protrusion 43.

Further, in the above embodiment, the electron gun having two intermediate electrodes has been described, but the present invention can be applied to an electron gun having one intermediate electrode or three or more intermediate electrodes.

Further, in the above embodiment, the third electrode and the fourth electrode
Although the auxiliary electrode is arranged between the electrode and the electrode, as shown in FIG. 9, the auxiliary electrode Gs may be arranged between the fourth electrode G4 and the fifth electrode G5. Since the other structure of this electron gun is the same as that of the electron gun of the above-mentioned embodiment, the same parts are designated by the same reference numerals and detailed description thereof will be omitted.

In the above embodiment, the QPF (Quadra P
Although the otential focus type electron gun has been described, the present invention is also applicable to other types of electron guns.

[0042]

The present invention has an auxiliary lens section for pre-focusing the electron beam emitted from the electron beam generating section and a main lens section for focusing the electron beam pre-focused by the auxiliary lens section on the phosphor screen. Focusing electrodes to which a dynamic focus voltage is applied, in which the main lens portion is sequentially arranged in the phosphor screen direction from the electron beam generating portion side, 1
In a color picture tube including an electron gun including one or a plurality of intermediate electrodes and a final accelerating electrode, and at least one asymmetrical lens formed by these electrodes, the auxiliary lens part forms a unipotential type electron lens. If three electrodes and one electrode that is connected to one of the intermediate electrodes and forms at least one asymmetrical lens in this auxiliary lens portion are configured, the AC voltage component of the dynamic focus voltage applied to the focusing electrode is formed. Is induced to the intermediate electrode that constitutes the main lens portion, the AC voltage component of the dynamic focus voltage is also induced to one electrode that forms the asymmetric lens of the auxiliary lens portion, and the AC voltage component of the dynamic focus voltage is The change of the lens action of the asymmetric lens of the main lens portion caused by being guided is changed to the auxiliary lens portion. It can be compensated by the change in the lens action of the asymmetrical lens, relatively by simple means, can be a resolution good color picture tube over the entire area of the screen from the central area to the periphery.

[Brief description of drawings]

FIG. 1 (a) is a front view showing in cross section the structure of an electron gun of a color picture tube which is an embodiment of the present invention, FIG.
(B) is a side view of the same.

FIG. 2 is a perspective view showing the shapes of electron beam passage holes on the auxiliary electrode side of the third grid and the fourth electrode side of the fifth electrode of the auxiliary lens section.

FIG. 3 is a diagram showing an overall configuration of a color picture tube which is an embodiment of the present invention.

FIG. 4 is an AC equivalent circuit diagram of a main part of an electron gun of a color picture tube which is an embodiment of the present invention.

FIG. 5 is a diagram for explaining the induction of an AC voltage component of the dynamic focus voltage applied to the fifth electrode of the electron gun of the color picture tube which is an embodiment of the present invention.

FIG. 6 is a diagram for explaining the shape of a beam spot obtained by the lens action of the auxiliary lens unit.

FIG. 7 (a) is an auxiliary electrode side of a third electrode and a fifth electrode.
FIG. 7 is a perspective view showing a different structure on the fourth electrode side of the electrode.
(B) is the sectional view.

FIG. 8 (a) is an auxiliary electrode side of a third electrode and a fifth electrode.
FIG. 8B is a sectional view showing a further different structure of the electrode on the side of the fourth electrode, and FIG.

FIG. 9 (a) is a front view showing in section the structure of an electron gun of another embodiment of the present invention, and FIG. 9 (b) is a side view thereof.

10A is a diagram of a horizontal deflection magnetic field generated by a deflection yoke of a self-convergence in-line type color picture tube, and FIG. 10B is a diagram of a vertical deflection magnetic field thereof.

FIG. 11 is a diagram showing the shape of a beam spot over the entire screen of a conventional self-convergence in-line type color picture tube.

FIG. 12 (a) is a front view showing in cross section the structure of a conventional self-convergence in-line type color picture tube electron gun, and FIG. 12 (b) is a side view thereof.

FIG. 13 (a) is a diagram showing a configuration of a main lens portion of an electron gun of a conventional self-convergence in-line type color picture tube, and FIG. 13 (b) shows potentials of respective electrodes of the main lens portion. It is a figure.

FIG. 14 is a diagram showing the shape of a beam spot at the center of the screen of a conventional self-convergence in-line type color picture tube.

[Explanation of symbols]

 2B, 2R ... A pair of side beams 2G ... Center beam 8 ... Resistor 10 ... Capacitance 22 ... Phosphor screen 25 ... Electron gun 28 ... Deflection yoke 30 ... Open hole 43 ... Protrusion 44 ... Recessed groove C ... Shield cup G1 ... First electrode G2 ... Second electrode G3 ... Third electrode G4 ... Fourth electrode G5 ... Fifth electrode G6 ... Sixth electrode Gm1 ... Intermediate electrode Gm2 ... Intermediate electrode Gs ... Auxiliary electrode KB, KG, KR ... Cathode

Claims (1)

[Claims] 1. An auxiliary lens unit for pre-focusing an electron beam emitted from an electron beam generator, and a main lens unit for focusing the electron beam pre-focused by the auxiliary lens unit on a phosphor screen. The main lens portion includes a focusing electrode to which a dynamic focus voltage is applied, which is sequentially arranged in the phosphor screen direction from the electron beam generating portion side, one or a plurality of intermediate electrodes, and a final accelerating electrode. In a color picture tube including an electron gun in which one asymmetric lens is formed, the auxiliary lens unit is connected to three electrodes forming a unipotential type electron lens and one of the intermediate electrodes. A color picture tube, characterized in that it comprises one electrode forming at least one asymmetric lens in its part.