JP3171455B2 - Color picture tube - Google Patents

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 achieving uniform focus quality.

[0002]

2. Description of the Related Art In general, a color picture tube deflects three electron beams emitted from an electron gun by a magnetic field generated by a deflection yoke mounted outside an envelope, and sorts the three electron beams by a shadow mask. The phosphor screen is formed so as to display a color image on the phosphor screen by scanning the phosphor screen horizontally and vertically.

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 and a pair of side beams passing on the same horizontal plane. 10
By combining a pincushion-type horizontal deflection magnetic field 1H shown in (a) and a deflection yoke for generating an asymmetric magnetic field consisting of a barrel-type deflection magnetic field 1V shown in (b), the three electron beams arranged in a line are self-concentrated. Self-convergence type in-line color picture tubes are widely used. In FIGS. 10A and 10B, 2G is a center beam, 2B and 2R are a pair of side beams.

However, the self-convergence type in-line type color picture tube has a problem that the sectional shape of the electron beam is distorted (deflection distortion) as the deflection angle is increased, and the resolution of the peripheral portion of the screen is deteriorated. That is, FIG.
As shown in the figure, the beam spot 4a at the center of the screen 3 is almost a perfect circle, but the beam spot 4b at the periphery of the screen 3
In addition to the elliptical high-luminance core portion 5 that is long in the horizontal direction, a low-luminance halo portion 6 that is long in the vertical direction is generated, and the resolution around the screen 3 is significantly deteriorated. Due to the non-uniformity of the deflection magnetic field, the distortion of the beam spot at the periphery of the screen 3 is caused by the horizontal focusing as shown by 2R 'for the side beam 2R in FIGS. 10 (a) and 10 (b). This is due to weakening and increased vertical focusing.

As one of the means for improving the resolution deterioration due to the above-mentioned deflection distortion, Japanese Patent Application Laid-Open No. Sho.
No. 947 discloses an electron gun shown in FIG. This electron gun has three cathodes KB, KG,
KR, first to sixth grids G1 to G6 having an integral structure sequentially arranged on the cathodes KB, KG, and KR, and two intermediate electrodes between the fifth grid G5 and the sixth grid G6. Gm1,
It is formed in a structure where Gm2 is arranged. In this electron gun, the main lens unit that focuses the three electron beams toward the phosphor screen includes fifth grids G5 and G5 serving as focusing electrodes.
The intermediate electrodes Gm1 and Gm2 and a sixth grid G6 as a final accelerating electrode. The two intermediate electrodes Gm1 and Gm2 receive a high voltage supplied to the final accelerating electrode along the electron gun. The voltage is divided into a predetermined voltage by the resistor 8 and supplied to the focusing electrode. A focusing voltage is supplied to the focusing electrode by synchronizing a constant DC voltage with an AC voltage component that changes in a parabolic manner in synchronization with the deflection of the deflection yoke. You.

[0006] With the above configuration, the main lens portion of the electron gun comprises the first grid G5 and the intermediate electrode Gm1 adjacent to the fifth grid G5. A pole lens is formed, and the intermediate electrode Gm2 and the sixth grid G6 adjacent to the intermediate electrode Gm2 form a second quadrupole lens that diverges the electron beam relatively vertically in the vertical direction. The first and second quadrupole lenses are balanced when the electron beam goes to the center of the screen,
At the center of the screen, a substantially circular beam spot is obtained. On the other hand, when it is deflected to the peripheral portion of the screen, the focusing voltage of the fifth grid G5 rises, and the potential difference between the fifth grid G5 and the intermediate electrode Gm1 becomes small, so that the first quadrupole lens becomes weak. The electron beam is relatively strongly affected by the second quadrupole lens. As a result, the vertically distorted deflection distortion is canceled.

However, as described above, in the fifth grid G5,
When a converging voltage in which a parabolically changing AC voltage component is superimposed on a constant DC voltage is applied, the fifth grid G5 and the intermediate electrode Gm1 adjacent thereto, the intermediate electrode Gm1 and the intermediate electrode Gm2, and the The electrode Gm2 and its adjacent sixth electrode
Since the capacitance exists between the grid G6 and the grid G6, the AC component that changes in a parabolic manner among the voltages applied to the fifth grid G5 passes through the capacitance to the intermediate electrodes Gm1 and Gm2.
And the potentials of the intermediate electrodes Gm1 and Gm2 change in synchronization with the deflection of the deflection yoke.

However, originally, this electron gun has an intermediate electrode Gm1,
Since the first quadrupole lens and the second quadrupole lens are designed to be balanced while keeping the potential of Gm2 constant, when the potentials of the intermediate electrodes Gm1 and Gm2 change as described above,
The balance between the quadrupole lens and the second quadrupole lens is lost, and the beam spot at the center of the screen is distorted.

FIG. 13 is a view for explaining the above-mentioned phenomenon. For example, a fifth grid G5 which is a focusing electrode shown in FIG.
, A DC voltage of about 28% of the high voltage applied thereto, a DC voltage of about 40% to the intermediate electrode Gm1 and a DC voltage of about 65% to the intermediate electrode Gm2 are synchronized with the deflection of the deflection yoke to the fifth grid G5. Assuming that the AC voltage component changing in a parabolic manner is superimposed, for example, assuming that the capacitances between the electrodes are the same, 2/2 of the AC voltage component changing in a parabolic manner superimposed on the fifth grid G5. 3 is the intermediate electrode Gm
1 and 1/3 are guided to the intermediate electrode Gm2. Then, corresponding to the diagram (a), it changes as shown by the broken lines 11a to 11c in the same manner as in FIG.
That is, the focusing voltage (solid line 10a) drops at the center of the screen as shown by the broken line 11a, but the reduction 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 12. it can. On the other hand, the intermediate electrode Gm
The potentials of Gm1 and Gm2 also fall below a predetermined value at the center of the screen as shown by broken lines 11b and 11c, respectively, but the potentials of the intermediate electrodes Gm1 and Gm2 are not adjusted. As a result, in the center of the screen, the first quadrupole lens is weak,
On the other hand, the second quadrupole lens becomes stronger. Therefore, FIG.
As shown in (1), the beam spot 4a at the center of the screen is distorted, and the resolution at the center of the screen is degraded. 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 is stronger than the design value and the second quadrupole lens is weaker. As a result, as shown in FIG. 15, the beam spot 4b around the screen 3 is also distorted, and the resolution is not sufficiently improved.

[0010]

As described above, three electron beams emitted from an electron gun and passing in the same horizontal plane and arranged in a row are arranged so that a horizontal deflection magnetic field has a pincushion type and a vertical deflection magnetic field has a barrel type. The self-convergence type in-line color picture tube which deflects by the magnetic field of the deflection yoke which generates a uniform magnetic field has a problem that the cross-sectional shape of the electron beam is distorted as the deflection angle increases, and the resolution of the peripheral portion of the screen is deteriorated. As a means for improving the resolution deterioration due to the deflection distortion, two intermediate electrodes are arranged between the focusing electrode and the final acceleration electrode constituting the main lens portion of the electron gun, and the final acceleration is applied to this intermediate electrode. A high voltage supplied to the electrode is divided to supply a predetermined voltage, and a focusing voltage obtained by superimposing a parabolic alternating voltage component on a constant direct voltage in synchronization with the deflection of the deflection yoke is applied to the focusing electrode. There are color picture tubes designed to be supplied.

However, even when the electron gun is configured as described above, of the voltage applied to the focusing electrode, an AC voltage component that changes in a parabolic manner is a static voltage interposed between the electrodes constituting the main lens portion. The beam is guided to the two intermediate electrodes via the capacitance, and the potential of each intermediate electrode changes in synchronization with the deflection of the deflection yoke, so that not only the beam spot at the center of the screen is distorted but also the beam spot at the periphery of the screen. However, there is a problem that the resolution is not sufficiently improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to constitute a color picture tube in which a good resolution can be obtained in the central portion and the peripheral portion of the screen.

[0013]

The present invention has a main lens portion for focusing an electron beam emitted from an electron beam forming portion on a phosphor screen, and the main lens portion focuses the electron beam from the electron beam forming portion toward the phosphor screen. An electrode, an electron gun arranged in the order of one or more intermediate electrodes and a final accelerating electrode, and a resistor for dividing a high voltage supplied to the final accelerating electrode and supplying a predetermined voltage to the intermediate electrode With
Electrodes other than the intermediate electrode and the final acceleration electrode are provided at the end of the picture tube.
Via a stem lead that passes through the stem
Each voltage is supplied and deflects the electron beam to change the phosphor
Changes synchronously with the deflection of the deflection yoke that scans on the screen
In a color picture tube in which a voltage to be applied is applied to a focusing electrode, a DC voltage is supplied between the focusing electrode and an intermediate electrode adjacent to the focusing electrode.
Connected to the electrode or through the stem lead
Then, an auxiliary electrode which is grounded in an alternating manner by being directly grounded was inserted.

[0014]

As described above, when an auxiliary electrode grounded in an alternating current manner is interposed between the focusing electrode and the intermediate electrode arranged adjacent to the focusing electrode, the gap between the focusing electrode and the auxiliary electrode is established. A capacitance is formed. On the other hand, when this auxiliary electrode is connected to the final accelerating electrode as an AC grounding means for the auxiliary electrode, the color picture tube generally has an internal conductive film formed on the inner surface of the funnel and an external conductive film formed on the outer surface of the funnel. The auxiliary electrode is AC grounded by a circuit consisting of the final acceleration electrode, the internal conductive film, the external conductive film, and the ground. Therefore, the AC voltage component that changes in synchronization with the deflection of the deflection yoke applied to the focusing electrode is grounded via the auxiliary electrode. On the other hand, the capacitance between the auxiliary electrode and the intermediate electrode adjacent thereto and the capacitance between the plurality of intermediate electrodes are short-circuited by the lead wire connecting the auxiliary electrode and the final acceleration electrode. As a result, an AC voltage component that changes in synchronization with the deflection of the deflection yoke is not superimposed on the intermediate electrode.

Further, even if the auxiliary electrode is grounded via, for example, a stem lead, an AC voltage component which changes in synchronization with the deflection of the deflection yoke is grounded via this auxiliary electrode. Thus, the AC voltage component that changes in synchronization with the deflection of the deflection yoke is not superimposed.

Therefore, only a predetermined DC voltage is applied to the intermediate electrode, and the first quadrupole lens formed by the focusing electrode and the intermediate electrode adjacent thereto, the final acceleration electrode, and the intermediate electrode adjacent thereto The second formed by
Lens function of the quadrupole lens can be normalized.

[0017]

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

FIG. 2 shows a color picture tube as an embodiment of the present invention. This color picture tube is composed of panel 20 and this panel.
A phosphor screen 22 comprising a three-color phosphor layer that emits blue, green, and red light is formed on the inner surface of the panel 20. Opposed to the screen 22, a shadow mask 23 having a large number of electron beam passage holes formed therein is arranged inside. In the neck 24 of the funnel 21, a center beam 2G and a pair of side beams 2B, which pass on the same horizontal plane,
An in-line type electron gun 25 for emitting three electron beams 2B, 2G and 2R arranged in a line composed of 2R and a resistor 8 for supplying a predetermined voltage to a predetermined electrode of the electron gun 25 are connected to the electron gun 25. It is arranged along. Further, from the inner surface of the large-diameter portion of the funnel 21 to the portion adjacent to the inner surface of the neck 24, an internal conductive film 26 is formed, and the outer conductive film 27 is formed on the outer surface of the large-diameter portion of the funnel 21.
Is formed by application.

The three electron beams 2B, 2G, and 2R emitted from the electron gun 25 are used to generate an asymmetric 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 deflection screen is deflected by the deflection yoke 28 and the phosphor screen is
The phosphor screen 22 is formed to display a color image by horizontally and vertically scanning the phosphor screen 22.

As shown in FIG. 1, the electron gun 25 includes three cathodes KB, KG, and KR arranged in a row in a horizontal direction, and three cathodes KB, KG, and KR for heating the three cathodes KB, KG, and KR. Heaters (not shown), first to sixth grids G1 to G6 sequentially arranged on the cathodes KB, KG, and KR toward the phosphor screen, a shield cup 30 attached to the sixth grid G6, And two intermediate electrodes Gm1 and Gm2 arranged between the fifth grid G5 and the sixth grid G6. Further, in the electron gun 25 of this example, the auxiliary electrode Gs is disposed between the fifth grid G5 and the intermediate electrode Gm1 adjacent thereto.

The electrodes of the electron gun 25 are formed in an integral structure, and the first and second grids G1, G2 are each composed of a relatively thin plate-like electrode.
Circular openings are provided corresponding to the three cathodes KB, KG and KR arranged in a row. Third and fourth grids G3, G4
Consists of cylindrical electrodes each having two cup-shaped electrodes abutting each other, and these electrodes are similarly provided with circular openings corresponding to the three cathodes KB, KG and KR arranged in a row. I have. The fifth grid G5 is composed of a pair of cylindrical electrodes formed by abutting two cup-shaped electrodes, each of which has a circular or non-circular shape corresponding to the three cathodes KB, KG, and KR arranged in a row. Opening is provided. The auxiliary electrode Gs is composed of a plate-like electrode having a relatively small thickness, and has a circular opening 32 corresponding to the three cathodes KB, KG and KR arranged in a row as shown in FIG.
However, the two intermediate electrodes Gm1 and Gm2 are each composed of a relatively thick plate-like electrode, and these electrodes have circular openings corresponding to the three cathodes KB, KG and KR arranged in a line. A hole is provided. Further, the sixth grid G6 is formed of a cylindrical electrode in which two cup-shaped electrodes are abutted, and this electrode has a circular or non-circular opening.

In the resistor 8, a terminal 33 provided at one end is connected to the sixth grid G6, and a terminal 34 provided at the other end is provided with a stem lead 36 ( FIG. 1) which passes through the stem 35 in an airtight manner . 2 ), or directly or via a variable resistor 37. Terminals 38 and 39 provided at the intermediate portion are connected to intermediate electrodes Gm1 and Gm2, respectively.
It is connected to the.

The following voltages are applied to the electrodes of the electron gun 25 during operation. That is, a voltage obtained by superimposing a video signal on a DC voltage of 180 V is applied to the cathodes KB, KG, and KR, the first grid G1 is grounded, and the second grid G1 is grounded.
G2 and the fourth grid G4 are connected in a tube to about 800V
The third grid G3 and the fifth grid G5 are connected in a tube in the same manner, and a DC voltage of 8 to 9 kV is superimposed with an AC voltage component that changes in a parabolic manner in synchronization with the deflection of the deflection yoke. Is applied. The auxiliary electrode Gs is connected to the sixth grid G6 in a tube, and a high voltage of about 30 kV applied to the sixth grid G6 through an anode terminal, an internal conductive film, a valve spacer attached to the shield cup 30, and the like. Is applied. Further, a voltage of about 40% of the high voltage (about 30 kV) divided by the resistor 8 is applied to the intermediate electrode Gm1.
Also, a voltage of about 60% is applied to the intermediate electrode Gm2.

By applying such a voltage, each cathode
The electron beams emitted from KB, KG, and KR diverge after forming a crossover near the first and second grids G1 and G2, and are prefocus lenses formed by the second and third grids G2 and G3. Receives the preliminary focusing, and further receives the preliminary focusing by the unipotential lens formed by the third, fourth, and fifth grids G2, G3, and G5, and thereafter, between the fifth grid G5 and the sixth grid G6. The formed main lens unit is finally focused and forms a beam spot on the phosphor screen.

In this case, in the main lens portion, a first beam mainly focused vertically in the vertical direction between a fifth grid G5 as a focusing electrode and an intermediate electrode Gm1 adjacent to the fifth grid G5. The quadrupole lens is also the intermediate electrode Gm
A second quadrupole lens that strongly diverges the electron beam mainly in the vertical direction is formed between 2 and the sixth acceleration electrode G6.

By the way, in such an electron gun 25,
Fifth grid G5 and intermediate electrode Gm forming the main lens portion
By arranging the auxiliary electrode Gs between 1 and 1, the following operation and effect can be obtained.

That is, the main lens portion of the electron gun (see FIG. 12) in which the auxiliary electrode is not arranged between the conventional fifth grid G5 and the intermediate electrode Gm1 adjacent to the fifth grid G5 is shown in FIG. As shown by the equivalent circuit, an AC equivalent circuit is obtained, and the capacitances C5m and C5m are respectively provided between the fifth grid G5, the intermediate electrodes Gm1 and Gm2, and the sixth grid G6.
mm and Cm6. As a result, the parabolic AC voltage component 10a applied to the fifth grid G5 becomes an AC source,
This AC voltage component 10a is guided to the intermediate electrodes Gm1 and Gm2 via the capacitances C5m and Cmm.

However, when the auxiliary electrode Gs is arranged between the fifth grid G5 and the intermediate electrode Gm1, as shown by an equivalent circuit in FIG. 5, the fifth grid G5, the auxiliary electrode Gs, the intermediate electrode Gm1,
Capacitances C5s, Csm, Cmm, and Cm6 are formed between the electrodes Gm2 and the sixth grid G6, respectively. In particular, the capacitance C5s between the fifth grid G5 and the auxiliary electrode Gs is formed inside the color picture tube. It is grounded via the capacitance CCRT of the tube itself formed by the conductive film and the external conductive film. Meanwhile, the auxiliary electrode
The capacitance Csm between Gs and the intermediate electrode Gm1 and the intermediate electrode
The capacitance Cmm between Gm1 and Gm2 is short-circuited by the lead wire 41 connecting the auxiliary electrode Gs and the sixth grid G6. As a result, the parabolic AC voltage component 10a applied to the fifth grid G5 is not induced to the intermediate electrodes Gm1 and Gm2, and only a predetermined DC voltage is applied to these intermediate electrodes Gm1 and Gm2. And the first and second quadrupole lenses perform the desired lens action.

Therefore, like the above-mentioned electron gun, the auxiliary electrode is provided between the fifth grid G5 and the intermediate electrode Gm1 adjacent thereto.
By arranging Gs, as shown in FIG. 6, the beam spot 4a at the center of the screen 3 can be made a perfect circle, and the halo of the beam spot 4b at the periphery of the screen can be eliminated, thereby improving the resolution of the entire screen. Can be.

Next, another embodiment will be described.

In the above embodiment, the auxiliary electrode disposed between the fifth grid and the intermediate electrode adjacent to the fifth grid is connected to the sixth grid, which is the final acceleration electrode, and is AC grounded. In the electron gun shown, the auxiliary electrode Gs is grounded outside the tube via a stem lead 36 which penetrates the stem airtightly. Other structures are the same as those of the above-mentioned electron gun.

With such a configuration, the main lens portion of the electron gun has a parabolic AC voltage component 10a applied to the fifth grid G5 as a focusing electrode, as shown by an equivalent circuit in FIG. The capacitance C5s formed between the five grids G5 and the auxiliary electrode Gs is grounded via the auxiliary electrode Gs, and the AC voltage component induced at the intermediate electrodes Gm1 and Gm2 can be greatly reduced. As a result, the intermediate electrodes Gm1 and Gm2 are almost in the same state as when a predetermined DC voltage is applied.
In addition, the second quadrupole lens can have an intended lens function.

In the above embodiment, the auxiliary electrode has a structure having three circular apertures.
As shown in (2), a structure having a long hole 42 having a major axis in the arrangement direction of the electron beams may be adopted. Regardless of the shape of the opening formed in this auxiliary electrode, the lens electric field of the first quadrupole lens formed between the fifth grid as the focusing electrode and the intermediate electrode adjacent thereto is formed. Give to
In order to minimize the influence, it is desirable to use a thin plate-shaped electrode. That is, when the thickness of the auxiliary electrode is large, FIG.
As shown in (c), penetration of an electric field occurs in the auxiliary electrode.
An electron lens is formed, and the electron beam is focused.
The first quadrupole lens applied to the electron beam
Change the use. On the other hand, if the auxiliary electrode is thin,
As shown in FIG. 9D, the penetration of the electric field is little in the auxiliary electrode.
Infinitely, no electron lens is formed. However, auxiliary
The strength of the first quadrupole lens, whether the electrode is thick or thin
Is different from the case without the auxiliary electrode,
Need to be coordinated with

In the above embodiment, the electron gun in which two intermediate electrodes are arranged on the main lens portion has been described. However, the present invention can be similarly applied to the case where one or three intermediate electrodes are provided. Further, in the above embodiment, the composite quadrapotential electron gun has been described. However, the present invention can be applied not only to other composite electron guns but also to a bipotential electron gun and a unipotential electron gun. .

Further, in the above embodiment, a color picture tube having an electron gun which emits three electron beams arranged in a line passing on the same plane has been described. The same can be applied to a color picture tube that emits four or more electron beams.

[0036]

According to the present invention, a main lens section for focusing an electron beam on a phosphor screen is arranged in the order of a focusing electrode, one or a plurality of intermediate electrodes, and a final acceleration electrode in a direction from the electron beam forming section toward the phosphor screen. In a color picture tube having an electron gun and a voltage that changes in synchronization with the deflection of a deflection yoke applied to the focusing electrode, an alternating current is grounded between the focusing electrode and an intermediate electrode adjacent to the focusing electrode. When the auxiliary electrode is inserted, the AC component of the voltage that changes in synchronization with the deflection of the deflection yoke is not superimposed on the intermediate electrode due to the AC grounding, and a color picture tube with good resolution over the entire screen can be obtained. it can.

[Brief description of the drawings]

FIG. 1A is a front view showing a cross section of a configuration of an electron gun of a color picture tube according to an embodiment of the present invention, and FIG.
Is a side view similarly shown in cross section.

FIG. 2 is a sectional view showing a configuration of a color picture tube according to an embodiment of the present invention.

3A is a plan view of an auxiliary electrode included in the electron gun, and FIG. 3B is a cross-sectional view taken along a line BB.

FIG. 4A is a waveform diagram of a voltage applied to a focusing electrode of a conventional electron gun shown for comparison with a main lens portion of an electron gun of a color picture tube according to an embodiment of the present invention; , FIG.
(B) is an equivalent circuit diagram of the main lens unit.

5A is a waveform diagram of a voltage applied to a focusing electrode of an electron gun of a color picture tube according to an embodiment of the present invention, and FIG. 5B is a diagram of a main lens portion of the electron gun. It is an equivalent circuit diagram.

FIG. 6 is a diagram showing a beam spot shape over the entire screen of a color picture tube according to an embodiment of the present invention.

FIG. 7 is a front view showing a cross section of a configuration of an electron gun of a color picture tube according to another embodiment of the present invention.

8 (a) is a waveform diagram of a voltage applied to a focusing electrode of the electron gun, and FIG. 8 (b) is an equivalent circuit diagram of a main lens portion of the electron gun.

9A is a plan view showing another structure having a different auxiliary electrode, FIG. 9B is a cross-sectional view taken along the line BB , and FIG.
Description showing the state of generation of an electric field when the thickness of the auxiliary electrode is large
FIG. 9D shows the generation of an electric field when the thickness of the auxiliary electrode is small.
It is explanatory drawing which shows a raw situation .

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

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

FIG. 12A is a front view showing a cross section of a configuration of a conventional self-convergence type in-line type electron gun;
FIG. 12B is a side view showing the same section.

FIG. 13A is a diagram illustrating a configuration of a main lens unit of the electron gun, and FIG. 13B is a diagram illustrating a potential of each electrode of the main lens unit.

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

FIG. 15 is a diagram showing a beam spot shape over the entire screen of the conventional self-convergence type in-line type.

[Description of Signs] 2B, 2R: A pair of side beams 2G: Center beam 8: Resistor 22: Phosphor screen 25: Electron gun 26: Internal conductive film 27: External conductive film 32: Opening 36: Stem lead 42 ... Opening KB, KG, KR Cathode G1 First grid G2 Second grid G3 Third grid G4 Fourth grid G5 Fifth grid (focusing electrode) G6 Sixth grid (final accelerating electrode) Gm1 Intermediate electrode Gm2… Intermediate electrode Gs… Auxiliary electrode

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-95446 (JP, A) JP-A-1-95444 (JP, A) JP-A-1-220341 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01J 29/48-29/50

Claims (1)

(57) [Claims] A main lens unit for focusing an electron beam emitted from an electron beam forming unit on a phosphor screen;
An electron gun in which the main lens portion is arranged in the order of a focusing electrode, one or more intermediate electrodes, and a final accelerating electrode in the direction of the phosphor screen from the electron beam forming portion;
A resistor for dividing a high voltage supplied to the final acceleration electrode and supplying a predetermined voltage to the intermediate electrode,
Electrodes other than the above-mentioned intermediate electrode and final accelerating electrode are
Through a stem lead that hermetically penetrates the provided stem
Each voltage is supplied and the electron beam is deflected to fluoresce
In synchronization with the deflection of the deflection yoke that scans the body screen
In a color picture tube varying voltage is applied to the focusing electrode, between the intermediate electrode adjacent to the focusing electrode and the focusing electrode, the DC voltage of the other intermediate electrode of the electrode
Is connected to the electrode to which the
A color picture tube characterized in that an auxiliary electrode which is grounded in an alternating manner by being directly grounded through a lead is interposed.