CN1018107B - Electron gun of picture tube - Google Patents

Abstract

An electron gun for a color picture tube has a first group of electrodes which generate electron beams and direct the electron beams along an initial path towards the phosphor screen and a second group of electrodes which form the main lens for focusing each of said electron beams on the phosphor screen , wherein the second electrode group is composed of the third, fourth, fifth and sixth electrodes that are linearly distributed from the first electrode group to the direction of the fluorescent screen, and the fourth electrode is composed of the first electrode group that is linearly distributed from the first electrode group to the direction of the fluorescent screen. 1. It consists of the second and third members. The second member has holes for transmitting electron beams. A constant potential is applied to the second member. Both the first member and the third member have holes for transmitting electron beams. Potentials are applied to the first and third members to vary the deflection current applied to the deflection coil for electron beam scanning.

Description

The present invention relates to kinescope electron guns, in particular, to electrodes forming the main lens of a color picture tube inline electron gun.

FIG. 2 is a plan view of a color picture tube with a conventional electron gun. A phosphor screen 3 coated with phosphors of three colors in turn is supported by the inner wall of the panel 2 of the glass envelope 1 . The respective central axes 17, 18 and 19 of the cathodes 6, 7 and 8 emitting electron beams are in line with the corresponding central axes of the hole portions of the first electrode G1 and the second electrode G2 respectively, and the central axes 17, 18 and 19 are also formed with the main The central axis of the aperture of the third electrode G3, the fourth electrode G4 and the fifth electrode G5 of the lens and the central axis of the aperture of the shield 15 are in a straight line, and the three central axes 17, 18 and 19 are fully parallel to each other in the same plane. The direction of this common plane is hereinafter referred to as the horizontal direction. The sixth electrode G6 is the last electrode that forms the main lens, and the central axes 9 and 10 of the two outer cylinders that extend from the aperture portion of the sixth electrode to the cylindrical portion inside the sixth electrode deviate outward from the corresponding central axis 17 and 19.

The three electron beams emitted by the corresponding cathodes 6, 7 and 8 are projected onto the main lens along the corresponding central axes 17, 18 and 19. These three central axes 17, 18 and 19 are called the original paths of the electron beams, as shown in Fig. 1 In the example shown, the main lens is composed of two electronic lenses, that is to say, the so-called single potential focusing electronic lens (UPF lens) formed by the third electrode G3, the fourth electrode G4 and the fifth electrode G5 and The so-called bipotential focusing electron lens (BPF lens) formed by the fifth electrode G5 and the sixth electrode G6 is combined. That is to say, a high voltage of about 20 to 30 kilovolts is applied to the above three places, and a focusing voltage of about 5 to 9 kilovolts is applied to the third electrode G3 and the fifth electrode On G5, a low potential of about 400 to 1000 volts is applied to the fourth electrode G4, which is roughly the same as the potential applied to the second electrode G2, and the electron beam projected on the main lens is controlled by the two electron lenses (UPF and BPF) lens) focusing, since the main lens is axisymmetric to the electron beam (central electron beam) projected along the central axis 18, after the main lens is focused, the central electron beam passes through the track along the central axis 18 directly. On the other hand, in the BPF lens (arranged along the outer central axes 17 and 19, formed by the fifth electrode G5 and the sixth electrode G6) among the electron lenses forming the main lens, since the central axes 9 and 10 of the sixth electrode G6 The electron beam is decentered outward, and the electron beam enters the interior of the sixth electrode along the central axis of the lens. As a result, the orbit of the electron beam deviates to the central axis 18 when the electron beam is focused. The electron beams projected to the main lens along the outer central axes 17 and 19 (outer electron beams) are focused toward the central electron beam while being focused by the main lens. Therefore, these three electron beams form one image point on the shadow mask 4, and are focused so as to overlap each other. This effect of focusing the electron beams is called convergence, and in particular, the convergence at the center of the screen is called static convergence (hereinafter abbreviated as STC). The electron beam is color-selected by the shadow mask 4, and only the parts that can excite the corresponding colored phosphor to emit light can reach the fluorescent screen 3 through the small hole of the shadow mask 4, and the external magnetic deflection coil 16 is installed adjacent to the glass shell 1, so that the electron beam Scan on fluorescent screen.

As we all know, if static convergence can be formed in the center of the frame, then the convergence of the entire frame can be accomplished by using an in-line electron gun with three electron beams in a horizontal plane and a so-called self-converging deflection coil that generates a non-uniform deflection field. However, this self-converging deflector coil has a problem in that the deflection defocus is too large, with the result that the resolution of the edge portion of the frame is reduced due to the inhomogeneity of the deflection field. Figure 3 schematically shows this phenomenon, where the electron beam spot is distorted due to deflection-induced defocusing.

In the edge portion of the frame, the high luminance portion 31 (nucleus) of the electron beam indicated by hatching expands in the horizontal direction, and the low luminance portion (halo) expands in the vertical direction. in frame The electron beam spots at the corners are skewed.

A method for overcoming this problem is disclosed in Japanese Patent Laid-Open №.74246/19860. Figure 4 shows a conventional electron gun. The fourth electrode G4 is divided into three parts along the direction from the cathodes 6 , 7 and 8 to the fluorescent screen 3 , namely the first member 121 , the second member 122 and the third member 123 . Substantially the same low potential as that applied to the second electrode G2 is applied to the first member 121 and the third member 123, respectively. The second member 122 has a horizontally elongated slot-shaped hole 12 . A potential that changes synchronously with the deflecting current applied to the deflecting coil, that is, the dynamic current, is applied to the second member 122 . If the degree of deflection is large, since the potential difference between the first member 121 and the third member 123 and the second member 122 increases, the magnification of the non-axisymmetric lens formed by the groove also increases, and as a result the electron beam The astigmatism of the light spot is also large. If the potential of the second member 122 is higher than that of the first member 121 and that of the third member 123, the astigmatism induced in the electron beam is vertical elongation of the nucleus and horizontal elongation of the halo. As a result, the astigmatism shown in FIG. 3 due to electron beam deflection can be canceled out, thereby improving the resolution of the edge portion of the frame. On the other hand, if the electron beam is not deflected, the formation of an asymmetric lens is prevented by eliminating the potential difference between the first member 121 and the third member 123 and the second member 122 so as to obtain an image that does not produce astigmatism in the central portion of the frame. condition, thus preventing resolution degradation.

In the conventional examples above, it is only disclosed that some electrodes can eliminate the astigmatism of deflection-induced focusing, without considering field curvature, which is another important factor of deflection-induced defocus. Due to this deflection-induced defocusing, even under the condition that the electron beam can be focused on the central part of the frame, at the edge part, the electron beam is focused before reaching the screen, so the electron beam is greatly expanded on the screen, and as a result, the The resolution of the edge portion of the color cathode ray tube frame is reduced.

Therefore, in the conventional example mentioned above, in addition to using the dynamic potential generating circuit In addition to correcting astigmatism, in order to correct field curvature, a circuit needs to be used to change the focus voltage at any time according to the deflection of the electron beam to change the magnification of the main lens. However, the focus voltage is a high voltage of 5 to 10 kV, so it is very difficult to make a circuit that can change the focus voltage at any time to correct field bending.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electron gun in which both astigmatism and field curvature can be corrected simultaneously by a single circuit which generates a relatively low dynamic voltage.

In order to correct the field curvature, when the electron beam is deflected to the frame edge portion, it is necessary to increase the potential of the fourth electrode G4 and decrease the magnification of the UPF lens formed by the third electrode G3, the fourth electrode G4 and the fifth electrode G5. If it is necessary to correct astigmatism, the fourth electrode G4 must be divided into first, second and third members, and a non-circular hole is opened on the second member, and the first and third members and the second member are made The potential difference changes synchronously with the deflecting current.

In this case, the electrical position of the second member is constant, while the potentials of the first member and the third member are a dynamic potential that varies with the biasing current.

In the conventional example shown in FIG. 4, if the potentials of the first member and the third member are fixed and the potential of the second member is raised, the effect of the potential increase is shielded by the first member and the third member. As a result, the amount of change in lens magnification is not sufficient to correct field curvature.

By opening a non-circular hole on the second member of the fourth electrode G4 and synchronously changing the potential difference between the first member and the third member and the second member with the deflection current, the error caused by the deflection can be corrected. Astigmatism. In this case, setting the electric position of the second member to a fixed value, increasing the potential of the first member and the third member during deflection can effectively reduce the lens magnification, thereby correcting the field curvature, because the third electrode G3 directly opposes the first member 121 , and the fifth electrode G5 directly opposes the third member 123 .

Another object of the present invention is to provide a structure of an electron gun in which a ratio The lower dynamic potential circuit can achieve both astigmatism correction and dynamic focus without any adverse effect on convergence.

In order to achieve dynamic focusing, when the electron beam is deflected to the edge area of the frame, it is necessary to increase the potential of the fourth electrode G4 and reduce the magnification of the UPF lens formed by the third, fourth and fifth electrodes G3, G4 and G5, If the astigmatism correction is to be completed simultaneously, it is necessary to divide the fourth electrode G4 into the first member 121, the second member 122 and the third member 123, open a non-circular hole on the second member, and make it compatible with the first member and the third member 123. The potential difference of the third member changes synchronously with the deflecting current. In this case, the structure for effectively realizing dynamic focusing is that the potential of the second component is constant, while the potentials of the first component and the third component are set as dynamic potentials that vary with the deflection current.

In order to remove the bad influence on the convergence, the non-circular holes opened on the second member are required to be vertically elongated slot-shaped holes. Due to this structure, if the electron beam has a large degree of deflection, increasing the dynamic voltage of the first member and the third member can reduce the magnification of the main lens, so that dynamic focusing can be achieved, and the electric potential of the second member is constant. The potential difference also increases at the same time, and as a result, the astigmatism caused by the deflection is eliminated, so the astigmatism can be increased in the opposite direction.

The astigmatism caused by deflection can be used to open a non-circular hole on the second member 122 of the fourth electrode G4 and change the second member 122 and the first member 121 and the third member 123 synchronously with the deflection current. The potential difference between the methods is corrected. In this case, the practice of performing control to reduce lens magnification, that is, dynamic focusing, is to raise the potential of the first and third members and lower the potential of the second member when deflected, because the third electrode indicated by the reference number 11 is connected with the The first member 121 is directly opposite, and the fifth electrode indicated by the numeral 13 is directly opposite to the third member 123 . On the other hand, in the conventional example shown in FIG. 4, if the potentials of the first and third members are not changed, and the potential of the second member is increased, the first member 121 and the third member 123 are affected by the influence of the potential increase. blocked, the The amount of change in lens magnification between the three electrodes G3 and the fifth electrode G5 is not sufficient to effectively achieve dynamic focusing. In this case, it is worth considering such a method. The potential of the second member is kept constant, but, according to the degree of deflection Lowering the potential of the second member produces an enhanced effect of correcting astigmatism.

By making the hole on the second member into a non-circular shape and adding a vertically elongated slotted hole, the convergence can be avoided due to the confusion caused by the horizontally elongated slotted hole, because the vertical slotted hole does not Influenced by neighboring holes.

The invention can be effectively used not only in color picture tubes, but also in single-gun picture tubes.

Figure 1 (a) is a horizontal sectional view of an electron gun based on an embodiment of the present invention;

Fig. 1(b) is a perspective view of a main part of the electron gun shown in Fig. 1(a);

Figure 2 is a horizontal sectional view of a color picture tube with a conventional electron gun;

Fig. 3 is the schematic diagram of the electron beam spot that conventional electron gun forms on the screen of color picture tube;

Figure 4(a) is a horizontal sectional view of another conventional electron gun;

Fig. 4(b) is a perspective view of a main part of the electron gun shown in Fig. 4(a);

Fig. 5, Fig. 6 and Fig. 9 illustrate the result of performance analysis of electron gun and conventional electron gun according to the design of the present invention;

Fig. 7, 8, 10, 12, 13 and 14 are the structural diagrams of other concrete realizations based on the electron gun electrode of the present invention;

Fig. 11 is to illustrate the potential wave form that is added based on the electron gun of the present invention;

Figure 15 (a) is a horizontal sectional view of another embodiment of an electron gun based on the present invention;

Figure 15(b) is a perspective view of a main part of the electron gun shown in Figure 15(a) picture;

Fig. 16 has shown the measurement result based on the electron gun performance of the present invention;

Fig. 17 is a front view and a vertical sectional view of another embodiment of an electron gun according to the present invention.

Referring to Fig. 1, an embodiment of the present invention will now be described in detail. A high potential (Eb) of 20 to 30 kV is applied to the sixth electrode G6 through the shield case 15. A medium potential (focus potential Vf) of 5 to 10 kilovolts is applied to the third electrode G3 and the fifth electrode G5, and a low potential of 100 to 1500 volts is applied to the fourth electrode divided into three members 121, 122' and 123. On the electrode G4, the third electrode G3, the fourth electrode G4 and the fifth electrode G5 form a UPF lens, the fifth electrode G5 and the sixth electrode G6 form a BPF lens, and the main lens composed of the above two lenses focuses the electron beam .

There is a longitudinally extending groove in the hole portion of the second member 122', the second member is located in the middle of the three members, and the potential is the same as that of the second electrode G2. A common voltage VG ₄ is applied to the first member 121 and the third member 123 respectively located on both sides of the second member 122'. The potential VG ₄ is determined by a dynamic current that varies synchronously with the deflecting current. When the deflection current is large and the electron deflection angle is large, the value of VG ₄ increases, and the magnification of the non-axisymmetric lens formed by the groove increases, thereby eliminating the astigmatism caused by the electron beam deflection.

FIG. 5 illustrates the results of computer analysis of the performance of the embodiment shown in FIG. 1. FIG.

The dimensions of the main lens of the electron gun used for analysis are as follows:

The diameter of the hole on the third electrode G3 (by the second electrode φ1.5

G2 side)

The hole diameter on the third electrode G3 (by the fourth electrode

Pole G4 side) φ4.0

Third electrode length 2.7

The first member 121 and the first member 121 of the fourth electrode G4

The diameter of the hole on the three-member 123 φ4.0

The first member 121 and the first member 121 of the fourth electrode G4

The length of three member 123 0.5

On the second member 122' of the fourth electrode G4

Hole diameter l ₁ φ4.0

Groove diameter l ₂ φ6.0

Groove width W 3.0

The second member 122' of the fourth electrode G4

Length 0.7

The diameter of the hole on the fifth electrode G5 (by the fourth electrode

Pole G4 side) φ4.0

The diameter of the hole on the fifth electrode G5 (by the sixth electrode

Pole G6 side) φ8.0

Fifth electrode G5 length 24.3

The diameter of the hole on the sixth electrode G6 φ8.0

(Unit: mm)

The voltage (Eb) applied to the sixth electrode G6 was 25 kV, and the voltage applied to the second member 122' of the fourth electrode G4 (the same electrode as that applied to the second electrode G2) was 650 V. The distance between the shadow mask 4 and the end point of the third electrode G3 facing the fourth electrode G4 is 340 mm, and the electron beams are focused on the shadow mask 4 .

Change the dynamic potential VG ₄ applied to the first member 121 and the third member 123 of the fourth electrode G4 so that the horizontal halo of the electron beam spot in the frame center area disappears, corresponding to the voltage VG ₄ at this time, to determine The value Vfh of the potential (Vf) of the third electrode G3 and the fifth electrode G5. The value V _fv of the potential (V _f ) of the third electrode G3 and the fifth electrode G5 when the vertical halo disappears can also be determined. As is clear from Fig. 5, the values of V _fh and V _fv coincide with each other when V _G4 is 150 volts, so that no astigmatism of the electron beams occurs, and thus ΔV _f is 0. As the value of V _G4 increases, the astigmatism increases, resulting in an increase in the astigmatism voltage ΔV _f (ie, V _fh minus V _fv ). In this case, the average value of _Vfh and _Vfv , that is, the average focus voltage _Vf decreases, which indicates that the magnification of the main lens decreases. Therefore, when V _G4 increases and V _f value remains unchanged, the distance between the focused position of the electron beam and the main lens increases.

In order to correct the astigmatism caused by deflection, it is necessary to increase the value of VG ₄ to increase the astigmatism of the main lens when the electron beam is deflected to the edge area of the frame. Astigmatism caused by the main lens increases the horizontal halo and suppresses the vertical halo. On the other hand, the astigmatism caused by deflection will increase the vertical halo, so these two kinds of astigmatism can cancel each other out, and the value of V _G4 can be corrected in each area of the frame by increasing the value of V G4 according to the degree of deflection. caused astigmatism.

The main lens magnification decreases as the value of VG ₄ increases, which extends the electron beam focus position towards the screen. Therefore, the position where the electron beam is focused can be aligned with the position of the screen, which were originally inconsistent due to field curvature.

As described above, increasing V _G4 in accordance with an increase in the degree of deflection can simultaneously correct for astigmatism due to electron beam deflection and field bending.

In the embodiment of the conventional device shown in FIG. 4, since the grooves on the fourth electrode G4 have a horizontally elongated shape and are very close to each other, there is a problem that the electron lenses corresponding to the two outer electron beams It is asymmetrical to the vertical plane containing the central axes 17 and 19, with the result that the direction of the outer electron beams is bent towards the middle electron beam, thereby adversely affecting the convergence, however, in the embodiment shown in Figure 1 , due to the use of vertically slender holes, this problem is solved.

Fig. 6 shows the relationship between the dynamic potential v ^' _G4 applied to the second member 122 of the fourth electrode G4 of the conventional electron gun shown in Fig. 4, and the relationship between the astigmatism voltage ΔV _f and the average focusing voltage V _f obtained by computer analysis As a result, the size of the electron gun main lens is the same as that used in the analysis shown in Fig. 5, and even though the groove is horizontal, it is also the same size as that used in the analysis shown in Fig. 5. As is clear from Fig. 6, the amount of change in _Vf due to the change in _VG4 ' is not sufficient to correct field curvature in conventional electron guns.

As mentioned above, the specific realization shown in FIG. 1 that the signal synchronized with the deflection current is applied to the first member 121 and the third member 123 of the fourth electrode G4 proves that this structure is effective in correcting field bending. . The conventional structure in which the signal is applied to the second member 122 is not suitable.

Fig. 7 has given an example, in this example in order to correct the astigmatism effectively on the surface facing the first member 121 ' of the second member 122 and the surface of the hole part of the third member 123 ', opened the narrow and long groove 71 of horizontal direction .

FIG. 8 is a specific implementation. The upper apertures of the first member 121 ″ and the third member 123 ″ of the fourth electrode G4 are separated by narrow and long through grooves 81 in the horizontal direction. When the dynamic potential V _G4 applied to the first member 121 ″ and the third member 123 ″ is higher than the potential V G4 applied to the second member 122 ′, the above-mentioned long and narrow horizontal groove 81 has a The astigmatic voltage changes to the positive level between the first member 121 "and the third member 123 "and the second member 122'. In this case, because V _G4 is lower than the third electrode G3 and the fifth electrode G5 potential (v _f ), between the third electrode G3 and the first member 121″ and between the fifth electrode G5 and the third member 123″ completes the effect of changing the astigmatism voltage to a negative level, when the value of V _G4 increases When it is large, the astigmatism generated between the first member 121 ″ and the third member 123 ″ and the second member 122 ′ increases, while the astigmatism generated between the third electrode G3 and the fifth electrode G5 weakens , in either case, the effect of changing the astigmatism toward the positive level is improved.

Fig. 9 has represented the effect analysis result of the embodiment shown in Fig. 8, and the size of the electron gun main lens that is used for this analysis is identical with the size of that main lens that is used for the analysis shown in Fig. 5, except first member 121 " and The horizontal narrow long groove 81 on the third member 123" has the following dimensions.

The first member 121" of the fourth electrode G4 and

The diameter of the groove of the third member 123″ l ₃ φ4.1

The first member 121" of the fourth electrode G4 and

Width W of the groove of the third member 123″ 2.0

(Unit: mm)

The potentials applied to the electrodes were the same as those used for the analysis shown in FIG. 5 .

Let's compare the results analyzed in Fig. 9 and Fig. 5. It can be seen from Fig. 9 that the V _G4 'values of the first member 121" and the third member 123" which make the astigmatism voltage ΔV _f zero are relatively high, being 660 Volts, which is substantially the same as the potential applied to the second member 122', because even though the potential of the second member 122' is equal to V _G4 ', the potential of the second member 122' is different from that of the third electrode G3 and the fifth electrode G5 , also will produce astigmatism in the embodiment shown in Fig. 1, on the other hand also because in the embodiment shown in Fig. 8 this astigmatism is offset by the astigmatism that produces because of the effect of horizontal narrow groove 81, Therefore, compared with the embodiment shown in FIG. 1, the magnification of the UPF lens formed by the third electrode G3, the fourth electrode G4 and the fifth electrode G5 is smaller in the embodiment shown in FIG. The diameter of the electron beam at the exit of the lens is larger. This can suppress the space charge effect of mutual repulsion of the electrons in the electron beam due to the Coulomb force and the electron beam broadening effect due to the thermal initial velocity in the direction of the electron beam radiation, that is, the increase of the electron beam spot on the screen caused by the thermal initial velocity distribution. effect.

Comparing the analysis results of Fig. 9 and Fig. 5, it is obvious that although the change amount of △V _f to the change of V _G4 ′ is roughly the same, the change amount of V _f is reduced to half. This indicates the fact that astigmatism and field curvature can be independently corrected by different configurations of slots on the first member 121" and third member 123" of the fourth electrode G4 according to the astigmatism characteristics of various deflection coils.

In the embodiment shown in FIG. 8 , the grooves 81 on the first member 121 ″ and the third member 123 ″ of the fourth electrode G4 directly face the third electrode G3 and the fifth electrode G5 respectively. Because the potential difference between the third electrode G3 and the fifth electrode G5 and the fourth electrode G4 is several thousand volts, the magnification of the lens is very large, even if these grooves are made smaller than those grooves on the second member 122', the effect It is also very large, so that even with horizontal grooves, due to their small size, they do not have the adverse effect on convergence encountered in the conventional embodiment shown in FIG. 4 .

In one embodiment shown in Figure 10(a) and Figure 10(b), the structure of the fourth electrode G4 is shown, which is designed to correct the electron beam light caused by the deflection at the corner of the frame. The rotation of the point. In the same manner as the example shown in FIG. 7, the grooves 101a and 103a are formed on the faces of the first member 121a and the third member 123a facing the second member 122a of the fourth electrode G4. The central axes of the grooves 101a and 103a are inclined relative to the horizontal plane. Therefore, the electron lens formed in this part is also inclined relative to the horizontal plane. The inclination direction of the lens is also opposite, and the potentials V _G4 ′ and V _G4 ″ that change synchronously with the deflection current are independently added to the first member 121a and the third member 123a. The same fixed potential as that applied to the second electrode G2 V _G2 is applied to the second member 122a. If V _G4 ′ and V _G4 ″ are larger than V _G2 , there occurs an effect that the electron beam spot rotates in the direction opposite to the groove inclination. That is to say, in the specific implementation shown in FIG. 10(a), viewed from the cathode side, the groove 101a on the first member 121a rotates counterclockwise relative to the horizontal plane, so the electron beam spot is rotated clockwise, On the other hand, the third member 123a shown in FIG. 10(b) has the effect of rotating the spot of the electron beam counterclockwise.

11 illustrates the waveforms of the potential V _G4 ′ of the first member 121a and the waveform of the potential V _G4 ″ of the third member 123a with solid lines and dot-dash lines, respectively, and the fixed potential V _G2 is drawn with double-dot-dash lines.

In the initial section of the vertical scanning period V, the electron beam spot is located at the top of the frame, and in the initial section of the horizontal scanning period H, the electron beam spot is located in the upper left corner of the frame. In this case, as can be clearly seen from Fig. 3 As can be seen clearly, due to the clockwise rotation of the deflection-induced astigmatism electron beam spot, as shown in Figure 10, in the initial section of the horizontal scanning period and the vertical scanning period, if V _G4 ″ is greater than V _G4 ′, then the first Three member 123a makes electron beam counterclockwise rotate the effect surpassing the effect of first member 121a, therefore can be corrected because the rotation of the electron beam spot that produces in the upper left corner of frame due to deflection focusing.When electron beam spot scans to the frame top In the middle, the values of V _G4 ′ and V _G4 ″ become substantially the same. Therefore, the effects of the first member 121a and the third member 123a cancel each other, which can prevent the rotation of the electron beam spot.

When scanning to the upper right corner of the frame, V _G4 ′ is greater than V _G4 ″, and as a result, the electron beam spot rotates clockwise due to the action of the first member 121a, so that the counterclockwise rotation caused by the deflection focusing can be canceled Then, make V _G4 ″ higher than V _G4 ′ during the horizontal blanking period, and make V _G4 ′ higher than V _G4 ′ gradually in the next horizontal scanning period H. The upper part is scanned vertically toward the center, and the rotation angle caused by deflection becomes smaller, so the difference between V _G4 ′ and V _G4 ″ must be reduced. It can be clearly seen from Fig. 3 that when the vertical scanning reaches the lower part of the frame, the frame The electron beam spot at the left end rotates counterclockwise, which is just the opposite of the situation in the upper half of the frame, so V _G4 ′ should exceed V _G4 ″ in the initial segment of the horizontal scan. When scanning to the bottom of the frame vertically, The rotation angle of the electron beam spot caused by deflection increases. Therefore, the difference between V _G4 ′ and V _G4 ″ should be gradually increased to improve the correction effect.

The difference between the average value of V _G4 ′ and V _G4 ″ and V _G2 is larger at the start and end of the horizontal scan H and the start and end of the vertical scan V, and the setting of the potential can improve the large astigmatism shown in Figure 3 The correction effect of the area.

As described above, not only the astigmatism of the electron beam spot can be corrected, but also the rotation of the corner spot can be corrected, so that a substantially circular spot can be obtained on the entire screen. This is due to the oblique grooves shown in Figure 10(a) and Figure 10(b) on the first member 121a and the third member 123a of the fourth electrode and V _G4 ' and V _G4 shown in Figure 11 ″ due to the potential waveform.

Fig. 12 has shown a concrete realization that is used for correcting above-mentioned electron beam spot rotation further effectively, and wherein the groove 101b and 103b that are inclined relative to the horizontal plane also starts on the second member 122a of the fourth electrode G4, and the direction of inclination needs to be consistent with the opening. In the opposite direction to the grooves of the first member 121a and the third member 123a of the second member 122a, the inclination directions of the grooves formed on both sides of the second member 122a should be opposite to each other.

Fig. 13 shows an embodiment also for correcting electron beam rotation. In this embodiment, the grooves 13 inclined relative to the horizontal plane are respectively formed on the surfaces of the first member 121b and the third member 123b of the fourth electrode G4 facing the third electrode G3 and the fifth electrode G5. FIG. 14 shows a specific Realization, wherein the grooves 14 inclined relative to the horizontal plane are respectively opened on the surfaces of the third electrode G3 and the fifth electrode G5 facing the fourth electrode G4. The above two specific implementations are used to make the gap between the third electrode G3 and the fourth electrode G4 The electron lens formed between the fourth electrode G4 and the fifth electrode G5 is inclined.

No matter in which embodiment, the inclination directions of the grooves opened on the two electrodes are opposite In order to make the electron lens tilt in the opposite direction, the rotation of the electron beam spot can be corrected by adding an independent potential that changes synchronously with the deflection current to the first member 121b and the third member 123b, and the effect is the same as that shown in FIG. 10 same as shown.

An advantage is shown based on the electron gun of the present invention, because the astigmatism caused by electron beam deflection to the color picture tube screen edge area and the astigmatism caused by field curvature can all be corrected simultaneously with a simple dynamic potential generating circuit, therefore, The electron beam spot diameter can be reduced and the uniformity of resolution can be improved in the peripheral area of the screen without providing a separate dynamic potential generating circuit for correcting astigmatism and field curvature.

Now, another embodiment of the present invention will be described with reference to Fig. 15(a) and Fig. 15(b). A high potential (E _b ) of 20 to 30 kV is applied to the electrode G6 marked 14 through the shield 15 . A medium potential (focus voltage _Vf ) of 5 to 10 kV is applied to electrode G3 marked 11 and electrode G5 marked 13, and a low voltage of 100 to 1500 volts is applied to electrode G4 marked 12, which Divided into three components 121, 122' and 123, the electrodes G3, G4 and G5 form a UPF lens, the electrodes G5 and G6 form a BPF lens, and the electron beam is focused by the main lens formed by combining the above-mentioned two lenses.

A vertically narrow slot is formed in the aperture portion of the second member 122' which is located in the middle of the three members. A first dynamic potential _VG4 ', which changes synchronously with the biasing current, is applied to this second member 122'. The common potential V _G4 is applied to the first member 121 and the third member 123 respectively located on both sides of the second member 122 ′. V _G4 is defined as a dynamic potential that changes synchronously with the biasing current. If the deflection current is large, causing a large degree of deflection of the electron beam, the value of V _G4 should be reduced to increase the magnification of the non-axisymmetric lens formed by the groove. Therefore, astigmatism caused by electron beam deflection is eliminated.

Fig. 16 has represented the result obtained by analyzing the effect of the embodiment shown in Fig. 15 by computer fruit.

The specific dimensions of the electron gun main lens used for this analysis are as follows:

The diameter of the hole on the electrode G3 (by the electrode G2

side) φ1.5

The diameter of the hole on the electrode G3 (by the electrode G4

side) φ4.0

The length of electrode G3 2.7

Electrode G4 holes on the first member and the third member

The diameter of φ4.0

The first and third members 121 of electrode G4 and

Length of 123 0.5

The diameter of the hole on the second member of the electrode G4 l ₁ φ4.0

Groove diameter l ₂ φ6.0

Groove width W 3.0

The length of the second member 122' of the electrode G4 is 0.7

The diameter of the hole on the electrode G5 (on the side of the electrode G4) φ4.0

The diameter of the hole on the electrode G5 (on the side of the electrode G6) φ8.0

Electrode G5 length 24.3

The diameter of the hole on the electrode G6 φ8.0

(Unit: mm)

The voltage (E _b ) applied to the electrode G6 marked 14 is 25 kV, and the distance from the shadow mask 4 to the side of the electrode G3 marked 13 facing the electrode G4 is 340 mm. The electron beams are focused on the shadow mask 4 .

By changing the first dynamic potential V G4 ' applied to the second member 122 of the electrode _G4 and the second dynamic potential V _G4 applied to the first member 121 and the third member 123, it can be obtained that when the central part of the screen electron beam Relationship between the value V _fh of the potential (V _f ) of electrodes G3 and G5 when the horizontal halo of the light spot disappears to the values of V _G4 and V _G4 ′ and the potential (V _f ) of electrodes G3 and G5 when the vertical halo disappears The relationship of the value of V _fv to the values of V _G4 and V _G4 '. It can be clearly seen from Fig. 16 that when V _G4 is 252 volts, V _G4 is 260 volts, and V _G4 ' is 700 volts, the values of Vfh and Vfv are the same, so there is no electron beam astigmatism. When V _G4 increases While V _G4 ' is increased by small astigmatism, that is, the image voltage ΔV _f , the average value of V _fh and V _fv , that is, the average focus voltage V _f is reduced, which indicates that the magnification of the main lens decreases. Therefore, when V _G4 increases and V _G4 ′ decreases to keep V _f constant, the distance between the electron beam focus position and the main lens increases, thereby realizing dynamic focusing.

In order to correct the astigmatism caused by deflection, when the electron beam is deflected to the edge area of the screen, the value of V _G4 must be increased and the value of V _G4 ′ must be decreased to increase the astigmatism of the main lens. The astigmatism of the main lens has the effect of expanding the horizontal halo and suppressing the vertical halo, and on the other hand, the astigmatism caused by the deflection has the effect of increasing the vertical halo. Thus, these two kinds of astigmatism cancel each other out, and by increasing the value of V _G4 and decreasing the value of V _G4 ' according to the degree of deflection, the astigmatism caused by deflection everywhere on the screen can be corrected.

As described above, the astigmatism caused by electron beam deflection can be corrected by increasing the value of V _G4 and decreasing the value of V _G4 ' according to the degree of deflection, while achieving dynamic focusing.

In this case, the method of fixing V _G4 ′ and only dynamically changing the value of V _G4 can realize astigmatism correction and dynamic focusing at the same time.

However, if the value of V _G4 ' is fixed at approximately 600 to 700 V, the astigmatism correction capability is reduced, resulting in a problem that the maximum value of ΔV _f decreases to 600 to 750 V. If V _G4 ' is further increased Larger, the astigmatism correction ability is further reduced.

On the other hand, the V _G4 ' value decreases, and the magnification of the UPF lens formed by the electrode G3 marked 11, the electrode G4 marked 12 and the electrode G5 marked 13 increases, and as a result, the electron beam is The main lens is strongly focused, and the diameter of the electron beam spot on the screen increases due to the space charge effect, so the resolution, especially in the central area of the screen, decreases.

FIG. 17 shows an embodiment. In this embodiment, horizontally narrow and long grooves are formed on the surfaces of the first member and the third member facing the second member, so as to improve the effect of astigmatism correction.

The invention provides an electron gun, using a common dynamic potential generating circuit, in which the astigmatism caused by electron beam deflection to the edge area of the color picture tube screen can be corrected, and dynamic focusing can be realized at the same time.

Since the vertical slots corresponding to the three electron beams are formed on the device according to the present invention, the mutual interference between them is very small, so that no adverse effect on the convergence performance occurs.

Since the second dynamic potential is applied to the second member 122' while the first dynamic potential is applied to the first member 121 and the third member 123 of the fourth electrode, the ability to correct deflection focusing is greater than that of the second member 122. The voltage is constant.

Claims (13)

1. An electron gun for a picture tube, the electron gun has a first electrode group that generates electron beams and guides the electron beams along an initial path to a fluorescent screen, and a second electrode group that forms a main lens that focuses the electron beams on the fluorescent screen, characterized in in: The second electrode group is composed of third, fourth, fifth and sixth electrodes distributed in a straight line from the first electrode group to the direction of the fluorescent screen; The fourth electrode is composed of a first member, a second member and a third member distributed in a straight line from the first electrode group to the direction of the fluorescent screen; said second member has a non-circular aperture for transmitting said electron beam, a constant potential is applied to said second member; and The first and third components have holes for transmitting the electron beam, and the electron beam is scanned at a high speed in the horizontal direction by being added to the deflection coil, and the deflection current that scans at a lower speed in the vertical direction is synchronized A varying potential is applied to said first member and third member. 2. A kinescope electron gun according to claim 1, wherein said non-circular hole has a larger dimension in a vertical direction perpendicular to the horizontal direction than in said horizontal direction. 3. An electron gun for a kinescope according to claim 2, wherein said potential applied to said first and third members increases as the deflection current of said electron beam increases. 4. A kinescope electron gun according to claim 1, wherein said potentials applied to said first and third members are common to each other. 5. A kinescope electron gun according to claim 1, wherein said first and third members opposed to said second member respectively have narrow and long grooves on at least one of two side faces, said The groove is adjacent to said hole portion and is parallel to said horizontal direction. 6. A kinescope electron gun according to claim 1, wherein at least one of said first or third members has a dimension in a vertical direction perpendicular to said horizontal direction which is smaller than that in said horizontal direction. the size of the hole. 7. A kinescope electron gun according to claim 2, wherein said first and third members each have a slant with respect to said horizontal direction, adjacent to said hole toward the center of said second member. connected narrow and long grooves, said grooves on said first member and said grooves on said third member are inclined in opposite ways to each other. 8. A kinescope electron gun according to claim 7, wherein said second member has elongated grooves on the faces opposite to said first and third members, said elongated grooves being in contact with said first and third members. Said facing grooves on the first and third members are inclined in opposite directions to the inclination directions. 9. A kinescope electron gun according to claim 1, wherein said elongated groove parallel to said horizontal direction is provided with holes on at least one face opposite to said third electrode and said first member. The partial abutment and the partial adjacency of the hole on at least one face opposite to said fifth electrode and said third member. 10. A kinescope electron gun according to claim 7, wherein potentials varying synchronously with said biasing current are respectively applied to said first member and third member, said first member at said first member. A first electron lens is formed on the passage of said electron beam between said second member and said passage of said electron beam between said second member and said third member forming a second electron lens, when said electron beam is deflected in a direction perpendicular to said horizontal direction, the magnifications of said first electron lens and said second electron lens are set to be substantially the same , and when said electron beam is deflected in a direction parallel to said horizontal direction, the magnification of one of said first electron lens and said second electron lens is set to be greater than The magnification of another electron lens. 11. A kinescope electron gun having first electrode means for generating an electron beam and directing said electron beam along an initial path to a phosphor screen and forming a main electrode means for focusing said electrons onto said phosphor screen A second electrode arrangement for a lens, characterized in that: Said main lens is formed by electrodes G3, electrodes G4, electrodes G5 and electrodes G6 distributed linearly from said first electrode arrangement towards said fluorescent screen; A high potential is applied to said electrode G6; middle potential is applied to said electrode G3 and electrode G5; Said electrode G4 is divided into a part from said first electrode arrangement toward said fluorescent screen, namely a first member, a second member and a third member; Apertures distributed on said second member for transmitting said electron beams are formed in a non-circular shape, wherein said apertures have a size smaller than that in the horizontal direction including an initial path corresponding to said apertures and The diameter in the plane perpendicular to the horizontal direction, along with the increase of the deflection degree of the electron beam, the potentials applied to the first member and the third member increase, and the The potential across said second member decreases. 12. A kinescope electron gun according to claim 11, wherein the potentials applied to said first member and said third member are the same. 13. A kinescope electron gun according to claim 11, grooves are formed adjacent to holes for transmitting said electron beams on both sides or one side surface of said first member and said third member. Each of said grooves has a plane of symmetry coincident with said horizontal direction.

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