JP2569027B2 - Electron gun for color picture tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrode forming a main lens of an electron gun for an in-line type color picture tube.

[Conventional technology]

FIG. 2 is a plan view of a color picture tube provided with a conventional electron gun. A fluorescent screen 3 in which phosphors of three colors are alternately applied is supported on the inner wall of the face plate 2 of the glass envelope 1. The respective central axes 17, 18, and 19 of the cathodes 6, 7, and 8 for generating an electron beam are formed by a first electrode G1, a second electrode G2, a third electrode G3, a fourth electrode G4, and a fifth electrode G4 that constitute a main lens. The central axes of the openings corresponding to the cathodes of the electrode G5 and the shielding cup 15 are coincident with each other. And these central axes 1
7, 18, and 19 are arranged substantially in parallel on a common plane.
The direction along this common plane is hereinafter referred to as the horizontal direction. Of the cylindrical portions protruding inward from the sixth electrode G6 from the opening of the sixth electrode G6, which is the final electrode constituting the main lens, the central axes 9 and 10 of the cylindrical portions arranged outwardly are centered. Axis 1
It is eccentric outward from 7,19.

The three electron beams emitted from each of the cathodes 6, 7, 8 enter the main lens along the central axes 17, 18, 19, respectively. The central axes 17, 18, and 19 are referred to as an initial path of the electron beam. First
In the illustrated example, the main lens is a so-called unipotential (Unpotential) formed by the third electrode G3, the fourth electrode G4, and the fifth electrode G5.
i-Potential Focusing) electronic lens (UPF lens),
It is composed of a combination of two electron lenses with a so-called Bi-Potential Focusing electron lens (BPF lens) formed by the fifth electrode G5 and the sixth electrode G6. The sixth electrode G6 has the same potential as the shielding cup 15, the conductive film 5 provided inside the glass envelope 1,
A high voltage of about 20 to 30 kV is applied. A focusing voltage of about 5 kV is applied to the third electrode G3 and the fifth electrode G5.
The fourth electrode G4 has a potential of 400 to 100 which is almost the same as that of the second electrode G2.
A low potential of about 0 V is applied. The electron beam incident on the main lens is the above two electron lenses (UPF and BPF lens)
Focusing. Since the main lens is formed axially symmetric with respect to the electron beam (center beam) incident along the central axis 18, the central beam is focused by the main lens and then goes straight on the trajectory along the central axis 18. . On the other hand, among the electron lenses constituting the main lens formed along the outer central axes 17, 19, the BPF lens formed by the fifth electrode G5 and the sixth electrode G6 has the central axis 9 of the sixth electrode G6. , 10 are shifted outward, the electron beam passes inside the center axis of the lens in the sixth electrode G6, and the electron beam trajectory is bent toward the center line 18 at the same time as the focusing. Thus, the electron beams (outer beams) incident on the main lens along the outer central axes 17, 19 are focused by the main lens and simultaneously concentrated in the central beam direction. From the above,
The three electron beams form an image on the shadow mask 4 and are further concentrated so as to overlap each other. The operation of concentrating each electron beam in this way is called convergence, and in particular, taking convergence at the center of the screen is called static convergence (hereinafter abbreviated as STC). Each electron beam is subjected to color selection by the shadow mask, and only the component that excites and emits the phosphor of the corresponding color passes through the opening of the shadow mask and reaches the phosphor screen. Further, since the electron beam is scanned on the phosphor screen, the external magnetic deflection yoke 16 is connected to the glass envelope 1.
Is provided in the peripheral portion of.

By combining an in-line electron gun in which the three electron beam paths are arranged on a horizontal plane as described above and a so-called self-convergence deflection yoke that forms a special non-uniform magnetic field distribution, STC is obtained at the center of the screen. If
It is known that convergence can be obtained over the entire other screen. However, in general, the self-convergence deflection yoke has a problem that the deflection aberration is large due to the non-uniformity of the magnetic field, and the resolution is reduced at the peripheral portion of the screen. FIG. 3 schematically shows how an electron beam spot is deformed by deflection aberration.

In the periphery of the screen, the high-brightness part of the electron beam indicated by the diagonal
31 (core) extends in the horizontal direction, low-luminance part 31 (halo)
Extends in the vertical direction. Furthermore, the electron beam spot is rotating at the corner of the screen.

Japanese Patent Application Laid-Open No. 61-74246 discloses one means for solving this problem. FIG. 4 shows an electron gun according to the conventional example. The fourth electrode G4 is divided into a first member 121, a second member 122, and a third member 123 from the cathodes 6, 7, 8 toward the phosphor screen. The first and third members 121 and 123 are given a low potential substantially equal to the potential of the second electrode G2. The second member 122 is provided with a horizontally long slit-like opening 12, and is provided with a potential that dynamically changes in synchronization with a deflection current supplied to the deflection yoke, that is, a dynamic potential. When the amount of deflection is large, the potential difference between the first and third members 121 and 123 and the second member 122 increases, so that the intensity of the non-axisymmetric lens formed by the slits increases, and large astigmatism occurs in the electron beam spot. . If the potential of the second member 122 is higher than the electrons of the first and third members 121 and 123, astigmatism generated in the electron beam has the effect of elongating the core in the vertical direction and extending the halo in the horizontal direction. Can eliminate the astigmatism caused by the electron beam deflection shown in (1), and can improve the resolution at the peripheral portion of the screen. On the other hand, when the electron beam is not deflected, the potential difference between the first and third members 121 and 123 and the second member 122 is eliminated so that an asymmetric lens is not formed and the condition that astigmatism does not occur at the center of the screen is obtained. As a result, resolution degradation does not occur.

[Problems to be solved by the invention]

In the above conventional example, only electrodes for canceling out astigmatism among deflection aberrations are specified, and no consideration is given to field curvature, which is important as other deflection aberrations. Due to this aberration, even if the condition that the electron beam is focused at the center of the screen is given, the electron beam is focused before reaching the screen at the periphery, and spreads greatly on the screen. The peripheral resolution is degraded.

Therefore, in the above conventional example, in addition to the dynamic potential generating circuit for correcting astigmatism, a circuit for dynamically changing the focusing voltage and changing the main lens strength in accordance with the amount of electron beam deflection is provided. Needs to be corrected. However, since the converging voltage is as high as 5 to 10 kV, it is not easy to configure a circuit that dynamically changes the voltage for correcting the field curvature.

Further, if the first and third member potentials are fixed and the second member potential is raised as in the conventional example of FIG. 4, the effect of the potential rise is shielded by the first and third members. No.
3, the amount of change in lens strength between the fourth and fifth electrodes is small,
There is a problem that field curvature cannot be effectively corrected.

An object of the present invention is to provide an electron gun capable of simultaneously correcting astigmatism and field curvature with a single circuit that generates a relatively low dynamic potential.

[Means for solving the problem]

In order to correct the field curvature, the potential of the fourth electrode G4 is raised when the electron beam is deflected to the periphery of the screen, and the third, fourth, and fourth potentials are increased.
The strength of the UPF lens constituted by the fifth electrodes G3, G4, G5 may be reduced. When performing astigmatism correction simultaneously, the fourth electrode G4 is divided into first, second, and third members, and a non-circular opening is provided in the second member, and the first, third, and second members are connected to each other. May be changed in synchronization with the deflection current.

At this time, the potential of the second member is fixed, and the potential of the first and third members is a dynamic potential that changes in accordance with the deflection current.

[Action]

By providing a non-circular opening in the second member of the fourth electrode and changing the potential difference between the first and third members in synchronization with the deflection current, astigmatism due to deflection can be corrected. At this time, if the potential of the second member is fixed and the potentials of the first and third members are increased during deflection, the third electrode G3 and the first member 12
1. Since the fifth electrode G5 and the third member are directly opposed, the operation of weakening the lens strength, that is, the field curvature correction can be effectively performed.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG. A high potential (E _b ) of 20 to 30 kV is applied to the sixth electrode G6 through the shielding cup 15. A moderate potential (converging voltage... _Vf ) of 5 to 10 kV is applied to the third electrode G3 and the fifth electrode G5. Fourth electrode G divided into three members 121, 122 ', 123
4 is applied with a low potential of 100 to 1500 V. 3rd, 4th, 5th
An UPF lens is formed by the electrodes G3, G4, and G5, and a BPF lens is formed by the fifth and sixth electrodes G5 and G6. The electron beam is focused by a main lens formed by a combination of the two electron lenses.

A vertically long slit is provided in the opening of the second member 122 'arranged at the center of the three members.
It is kept at the same potential as the electrode G2. The same potential _VG4 is applied to the first and third members 121 and 123 arranged on both sides of the second member 122 '. V _G4 is a dynamic potential that changes in synchronization with the deflection current. When the deflection current is large and the amount of electron beam deflection is large, the value of _VG4 is increased to increase the strength of the non-axisymmetric lens formed by the slit, thereby canceling astigmatism associated with electron beam deflection.

FIG. 5 is a result of analyzing the effect of the embodiment of FIG. 1 using a computer.

The specific dimensions of the electron gun main lens analyzed are as follows.

Hole diameter of the third electrode G3 (second electrode G2 side) φ1.5 〃 (fourth electrode G4 side) φ4.0 Third electrode G3 length 2.7 Hole diameter of the first and third members 121 and 123 of the fourth electrode G4 φ4 .0 〃 Electrode length 0.5 Second member 122 'opening diameter l ₁ φ4.0 of fourth electrode G4 〃 Slit opening diameter l ₂ φ6.0 ス リ ッ ト Slit width W 3.0 電極 Electrode length 0.7 Opening diameter of fifth electrode G5 ( Φ4.0 〃 (Sixth electrode G6 side) φ8.0 Fifth electrode G5 length 24.3 Hole diameter of sixth electrode G6 φ8.0 (Unit: mm) Also, application to sixth electrode G6 The voltage (E _b ) is 25 kV, and the voltage applied to the second member 122 ′ of the fourth electrode G 4 (the same as the voltage applied to the second electrode G 2) is 650 V. Shadow mask 4 and 3
The distance between the end of the electrode G3 on the fourth electrode G4 side is 340 mm, and the electron beam is focused on the shadow mask 4.

Varying the dynamic potential V _G4 applied to the first and third members 121 and 123 constituting the fourth electrode G4, for the value of each V _G4, the when the horizontal halo electron beam spot disappears at the center of the screen 3. The value V of the potential (V _f ) of the fifth electrode
_fh and the value V _fV of the potential (V _f ) of the third and fifth electrodes when the vertical halo disappears are obtained. V _G4 is 150V from Fig.5
In this _case, the values of V _fh and V _fV become equal, the astigmatism does not occur in the electron beam, and ΔV _f becomes zero. Increasing the value of V _G4, astigmatism voltage [Delta] V _f astigmatism becomes strong, that is, a voltage value obtained by subtracting the V _fV from V _fh is increased. At this time, the average value of V _fh and V _fV , that is, the average value of the focusing voltage ▲
The value of ▼ decreases. This indicates that the main lens strength is weak. Therefore, if _Vf is kept constant when _VG4 is increased, the distance between the position where the electron beam is focused and the main lens is extended.

In order to correct the astigmatism caused by the deflection, it increases the value of V _G4 when the electron beams are deflected to the periphery of the screen, it is sufficient to increase the astigmatism by the main lens. Astigmatism caused by the main lens has the effect of expanding the horizontal halo and suppressing the vertical halo. On the other hand, astigmatism due to deflection has the effect of strengthening the halo in the vertical direction, so that these astigmatisms can be eliminated. V according to the amount of deflection
_Increasing the value of _G4 can correct astigmatism due to deflection in each part on the screen.

At the same time, as the _VG4 rises, the main lens strength weakens and the electron beam focusing position is extended in the screen direction, so that the electron beam focusing position, which did not match due to field curvature, matches the screen position. be able to.

Thus, by the raising is accompanied the value of V _G4 to increase the amount of deflection can correct astigmatism and curvature of field generated in the electron beam deflection at the same time.

Further, in the conventional example shown in FIG. 4, the slit openings of the fourth electrode G4 are close to each other because the slit openings are horizontally long. Therefore, the electron lenses for both outer electron beams are asymmetric with respect to the vertical plane including the respective central axes 17 and 19, and the outer electron beam is bent in the direction of the central beam, which adversely affects convergence. Occurs. In the embodiment shown in FIG. 1, a vertically long opening is provided, so that this problem is also solved.

The Figure 6, a dynamic potential V _G4 applied to the second member 122 of the fourth electrode G4 of the electron gun in the conventional example of FIG. 4, astigmatism voltage [Delta] V _f and the focusing voltage average value ▲ ▼ and the The results of the relationship obtained by computer analysis are shown. At this time, the dimensions of the electron gun main lens are the same as those used in the analysis of FIG. However, the slits are provided in the horizontal direction, but the slit dimensions are also the same as the analysis conditions in FIG.
From the results shown in FIG. 6, in the electron gun shown in the conventional example,
It can be seen that the amount of change of ▲ with respect to the change of V _G4 ′ is small, and there is almost no field curvature correction effect.

Therefore, in order to correct the curvature of field, the first and third members 131 and 123 of the fourth electrode G4 must be provided as in the embodiment of FIG.
It is appropriate to apply a signal synchronized with the deflection current.
The configuration for applying the voltage to the second member 122 as in the conventional example is inappropriate.

FIG. 7 shows that in order to perform astigmatism correction more effectively,
In this example, a horizontally long groove 71 is provided in an opening of a surface of the fourth electrode G4 facing the first member 121 'and the third member 123' facing the second member.

FIG. 8 shows an embodiment in which a horizontally long through slit 81 is provided in the opening of the first member 121 "and the third member 123" of the fourth electrode G4. When the dynamic potential V _G4 applied to the first and third members 121 ″ and 123 ″ is higher than the potential of the second member 122 ″, the horizontal through slit 81 described above makes the first and third members 121 ″ and 123 ″. "and the second member 122 has the effect of changing the astigmatism voltage in the positive direction between the 'and V _G4 third, fourth
Since the potential of the five electrodes G3 and G5 is lower than the potential (V _f ), the astigmatism voltage is changed in the negative direction between the third electrode G3 and the first member 121 ″ and between the fifth electrode G5 and the third member 123 ″. effective. When V _G4 increases, astigmatism generated between the first and third members 121 ″, 123 ″ and the second member 122 ′ increases, and the third and fifth electrodes G3, G5 increase.
And the astigmatism occurring between them becomes weaker. In any case, the effect of changing astigmatism in the positive direction is enhanced.

FIG. 9 shows an analysis result of the effect when the embodiment of FIG. 8 is used. The dimensions of the electron gun main lens analyzed were
The dimensions are the same as those of the main lens used in the analysis of FIG. 5, except that horizontal slits 81 having the following dimensions are provided in the third members 121 ″ and 123 ″.

The slit opening diameter l ₃ φ4.1 ス リ ッ ト slit width W 2.0 (unit: mm) of the first and third members 121 ″ and 123 ″ of the fourth electrode G4. The electrode potential was also used in the analysis shown in FIG. Are identical.

9 is compared with the analysis result of FIG. 5, FIG. 9 shows that the first and second values for making the astigmatism voltage ΔV _f zero are shown in FIG.
The third member 121 ', 123''has a higher value of the 660V, second member 122' potential V _G4 seen that substantially coincides with the potential of. This is because in the embodiment of FIG. 1, there is a potential difference between the second member 122 'and the third and fifth electrodes G3 and G5 even if the potential of the second member 122' matches the _VG4 '. For this reason, astigmatism occurs, whereas in the embodiment shown in FIG. 8, the astigmatism can be canceled out by the astigmatism generated by the effect of the horizontal slit 81. Therefore, in the embodiment of FIG. 8, the third, fourth, and fifth electrodes G3, G are compared with the embodiment of FIG.
4, The strength of the UPF lens formed by G5 can be weakened, and the diameter of the electron beam at the exit can be enlarged at the main lens. As a result, the electron in the beam repels each other due to Coulomba, that is, the space charge effect, and the effect that the beam expands due to the beam initial thermal velocity of each electron, that is, the effect on the screen based on the thermal initial velocity dispersion. The expansion of the electron beam spot is suppressed.

Also, comparing the analysis result of FIG. 9 with FIG. 5,
It can be seen that the amount of change of ΔV _f with respect to the change of V _G4 ′ is almost the same, while the amount of change of Δ ▼ is reduced to about half. This corresponds to the first and third members 121 ″, 12 ″ of the fourth electrode G4.
This shows that the amount of correction for astigmatism and curvature of field can be adjusted independently according to the aberration characteristics of various deflection coils by making the 3 ″ slits various shapes.

In the embodiment of FIG. 8, the first and third members 121 ″ of the fourth electrode G4,
The 123 ″ slits 81 directly face the third and fifth electrodes G3 and G5, respectively. The potential difference between the third and fifth electrodes G3 and G5 and the fourth electrode G4 is several kV, and the lens strength is high. , The second member 12
Even when the slit size is extremely small, the effect obtained is large as compared with the 2 'slit. Therefore, despite the provision of the horizontal slits, the dimensions are small, so that the convergence characteristics are not adversely affected unlike the conventional example shown in FIG.

The embodiment of FIG. 10 shows the configuration of the fourth electrode 4 for correcting the rotation of the electron beam spot at the corner of the screen caused by deflection. Like the zero in FIG. 7, the fourth electrode
The first and third members 121a and 123a of G4 are provided with grooves 101a and 103a on the surface facing the second member 122a, and the central axes of the grooves 101a and 103a are inclined with respect to the horizontal plane. I have.
Therefore, the symmetry plane of the electron lens formed in this portion is also inclined with respect to the horizontal plane. Since the directions of inclination are opposite to each other in the first member 121a and the third member 123a, the directions of inclination of the electron lenses provided in the vicinity of each member are also opposite. On the first member 121a and the third member 123a, potentials V _G4 ′ and V _G4 ″ that change independently in synchronization with the deflection current are respectively provided.
A constant potential _VG2 common to the G2 electrode is applied to the second member 122a. When V _G4 ′ and V _G4 ″ are larger than V _G2, it has the effect of rotating the electron beam spot in the direction opposite to the inclination of each groove. That is, in the embodiment of FIG. Since the groove 101a rotates counterclockwise with respect to the horizontal plane as viewed from the cathode side, the electron beam spot is rotated clockwise, while the third member 123a has the effect of rotating the electron beam spot counterclockwise. .

FIG. 11 shows the potential _VG4 'of the first member 121a and the second member 123a.
An example of the waveform of the potential V _G4 ″ is indicated by a solid line and an alternate long and short dash line, respectively. The constant potential V _G2 is indicated by a two-dot chain line.

At the beginning of the vertical scanning period V, the electron beam spot is at the top of the screen, and at the beginning of the horizontal scanning period H, it comes to the upper left corner of the screen. At this time, the third
As can be seen, the electron beam spot rotates clockwise due to deflection aberration. If V _G4 ″ is set to be larger than V _G4 ′ as shown in FIG. 10 at the start of horizontal and vertical scanning, the effect of rotating the electron beam in the counterclockwise direction of the third member 123a is reduced by the effect of the first member 121a. Because it exceeds the effect,
The rotation of the electron beam spot due to the deflection aberration at the upper left corner of the screen can be corrected. When the electron beam spot is scanned horizontally to the top center of the screen,
Since V _G4 ′ and V _G4 ″ have substantially the same value, the first member 121 a
And the effect of the third member 123a cancel each other, and the electron beam spot does not rotate.

When scanning is further performed to the upper right corner of the screen,
V _G4 ′ becomes a value larger than V _G4 ″, and the electron beam spot rotates clockwise due to the effect of the first member 121a, thereby canceling the counterclockwise rotation due to the deflection aberration.
During the horizontal retrace period, V _G4 ″ is again set to exceed V _G4 ′, and during the subsequent horizontal scanning period H, as described above,
V _G4 ′ is gradually made larger than V _G4 ″. As the electron beam spot is scanned vertically from the top of the screen to the center, the angle of rotation due to deflection becomes smaller.
The difference between the values of _G4 'and _VG4 "is reduced. When the vertical scanning is performed to the lower part of the screen, as can be seen from FIG. On the other hand, since it rotates counterclockwise, the value of V _G4 '
V _G4 ″. Vertical scanning to the lowermost end of the screen increases the rotation angle of the electron beam spot due to deflection, so the difference between V _G4 ′ and V _G4 ″ is gradually increased and corrected. Try to be more effective.

Further, the difference between the average value of V _G4 ′ and V _G4 ″ and V _G2 is large at the start and end of the horizontal scan H and at the start and end of the vertical scan V. That is, as shown in FIG. The potential is set so that the correction effect becomes strong in the portion where the astigmatism is large as shown.

As described above, the first and third electrodes of the fourth electrode G4 shown in FIG.
Not only the astigmatism of the electron beam spot but also the rotation of the spot at the corners is formed by the inclined groove structure provided on the members 121a and 123a and the V _G4 ′, V _G4 ″ potential waveform shown in FIG. Can be corrected in the same manner, and a substantially circular spot can be obtained over the entire screen.

FIG. 12 shows an embodiment in which grooves 101b and 103b inclined with respect to the horizontal plane are also provided in the second member 122a of the fourth electrode G4 in order to more effectively correct the rotation of the electron beam. The direction of the inclination needs to be opposite to the direction of the grooves of the opposing first member 121a and third member 123a. Therefore, the second
The inclination directions of the grooves on both the front and back sides of the member 122a must be reversed.

FIG. 13 is a view similar to FIG. 13 showing the surface of the fourth electrode G4 facing the third electrode G3 and the fifth electrode G5 of the first and third members 121b and 123b to correct the rotation of the electron beam spot. FIG. 14 shows the fourth groove of the third and fifth electrodes G3 and G5.
In the embodiment in which the electron lens formed between the third and fourth electrodes and between the fourth and fifth electrodes is inclined by providing the groove portion 14 inclined with respect to the horizontal plane on the surface facing the electrode G4. is there.

In each embodiment, the inclination directions of the grooves provided in the two electrodes are made opposite to each other, and the respective electron lenses are inclined in opposite directions. The rotation of the electron beam spot can be corrected in the same manner as in the embodiment of FIG. 10 by giving independent potentials that change in synchronization with the deflection current to the first member 121b and the third member 123b.

[Effects of the Invention] According to the present invention, a single dynamic potential generation circuit corrects astigmatism caused by electron beam deflection toward the periphery of a color picture tube and also effectively corrects field curvature. Can be. Therefore, the diameter of the electron beam spot at the periphery of the screen can be reduced without providing separate dynamic potential generation circuits for astigmatism correction and field curvature correction, and the uniformity of resolution can be improved.

[Brief description of the drawings]

FIG. 1 (a) is a diagram showing a horizontal cross section of an electron gun according to one embodiment of the present invention, FIG. 1 (b) is a perspective view of a main part of FIG. 1 (a),
FIG. 2 is a view showing a horizontal cross section of a conventional color picture tube provided with an electron gun, FIG. 3 is a view schematically showing an electron beam spot shape of each part of a color picture tube screen by the conventional electron gun, and FIG. ) Is a diagram showing a horizontal cross section of another conventional electron gun, and FIG.
4 (b) is a perspective view of the main part of FIG. 4 (a), FIGS. 5, 6 and 9 are diagrams showing analysis results of the characteristics of the present invention and the conventional electron gun, FIGS. 8, 10, 12, 13
FIG. 14 and FIG. 14 are diagrams showing an electrode structure of another embodiment of the present invention, and FIG. 11 is a diagram showing an example of a potential waveform applied to the electron gun of the present invention. 1 ... glass envelope, 2 ... face plate, 3 ...
Phosphor screen, 4 ... shadow mask, 5 ... conductive film, 6, 7, 8
… Cathode, G1… First electrode, G2… Second electrode, G3… Third electrode, G4… Fourth electrode, G5… Fifth electrode, G6… Sixth
Electrode, 15… Shield cup, 16… External magnetic deflection yoke,
17,18,19 …… Electron beam initial path, 121,121 ′, 122 ″, 12
1a, 121b,..., The first member of the fourth electrode, 122, 122 ′, 122a,.
The second member of the fourth electrode, 123, 123 ', 123 ", 123a, 123b ...
The third member of the fourth electrode.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masakazu Fukushima 1-280 Higashi-Koigabo, Kokubunji-shi Inside the Central Research Laboratory, Hitachi, Ltd. (56) References JP-A-61-74246 (JP, A) JP-A-61-42841 (JP, A) JP-A-61-99249 (JP, A)

Claims (10)

(57) [Claims] A first electrode group for generating a plurality of electron beams and directing the electron beams to a phosphor screen along initial paths parallel to each other on a horizontal plane; And a second electrode group constituting a main lens for focusing on the first and second electrode groups, wherein the second electrode group is a third electrode group arranged in order from the first electrode group toward the phosphor screen. A focusing voltage is applied to the third and fifth electrodes, a voltage higher than the focusing voltage is applied to the sixth electrode, and a voltage lower than the focusing voltage is applied to the fourth electrode. A plurality of electron lenses are formed, and the fourth electrode includes first, second, and third members sequentially arranged from the first electrode group toward the phosphor screen, and the second member transmits the electron beam. Has a non-circular opening for passing A constant potential is applied, the first
The third member has an opening through which the electron beam passes, and is applied with a potential that changes in accordance with a deflection current supplied to a deflection yoke for scanning the electron beam. Electron gun for color picture tubes. 2. The non-circular opening according to claim 1, wherein said non-circular openings have different diameters centered on said initial passage.
The opening having a large diameter is formed in a slit shape with respect to the opening having a small diameter, the opening having a large diameter is perpendicular to the horizontal plane, and the opening having a small diameter is oriented in the horizontal plane. An electron gun for a color picture tube, wherein 3. The method according to claim 2, wherein
And a potential applied to the third member is increased with an increase in the electron beam deflection current. 4. The method according to claim 1, wherein
And a potential applied to the third member is a common potential. 5. The method according to claim 1, wherein:
An electron gun for a color picture tube, wherein each of the third member and the third member has a long groove parallel to the horizontal plane around an opening on at least one of the surfaces facing the second member. 6. The method according to claim 1, wherein
And at least one opening of the third member is composed of two openings having different diameters centered on the initial passage, the large diameter opening is formed in a slit shape with respect to the small diameter opening, and the small diameter opening is formed. An electron gun for a color picture tube, wherein an opening having a large diameter is provided in a direction perpendicular to the horizontal plane, and an opening having a large diameter is provided in a direction of the horizontal plane. 7. The method according to claim 2, wherein
And the third member each has a long groove inclined with respect to the horizontal plane around the opening on the surface facing the second member, and the groove is opposite to the first and third members in the directions opposite to each other. An electron gun for a color picture tube, characterized by being inclined. 8. The method according to claim 7, wherein
An electron gun for a color picture tube, characterized in that the member has a long groove inclined in a direction opposite to the groove of the member facing the first and third members on a surface facing the first and third members. 9. The method according to claim 1, wherein
A long groove parallel to the horizontal plane is provided around an opening on at least one of the opposing surfaces of the electrode and the first member and the opposing surface of the fifth electrode and the third member. Electron gun for a color picture tube. 10. A method according to claim 7, wherein a potential changing in synchronization with said deflection current is separately applied to said first and third members, respectively. A first electron lens is formed in the electron beam path, and a second electron lens is formed in the electron beam path between the second and third members. Each of the electron beams is directed in a direction perpendicular to the horizontal plane. When deflected to
When the second electron lens intensities are substantially matched and each of the electron beams is deflected also in a direction parallel to the horizontal plane, one of the first and second electron lenses is changed in intensity. An electron gun for a color picture tube, wherein the strength of the other electron lens is made stronger.