JP3360863B2 - Electron gun for 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 picture tube electron gun, for example, a color picture tube electron gun.

[0002]

2. Description of the Related Art A conventional color picture tube having an electron gun for a color picture tube will be described with reference to FIG.

First, a phosphor screen 3 having phosphors of three colors alternately coated in stripes is supported on the inner wall of the face plate portion 2 of the glass envelope 1. The central axes 15, 16, 17 of the cathodes 6, 7, 8 are G1 (first grid) electrodes 9,
G2 (second grid) electrode 10, G constituting the main lens
The third (third grid) electrode (focusing electrode) 11 and the center axis of each opening corresponding to each cathode of the shielding cup 13 are aligned and arranged substantially parallel to each other on a common plane.

The central axis of the central aperture of the G4 (fourth grid) electrode (accelerating electrode) 12, which is the other electrode constituting the main lens, coincides with the central axis 16, but both outer sides. The central axes 18 and 19 of the apertures do not coincide with the corresponding central axes 15 and 17, respectively, and are slightly displaced outward.

The three electron beams emitted from each cathode enter the main lens along the central axes 15, 16 and 17.

In the electrodes constituting the electron gun for the color picture tube, each electrode other than the G4 electrode 12 is a pin (electrically connected to each electrode in the neck portion 20 of the glass envelope 1). An electric potential is applied from the outside of the glass envelope through the stem pin 21.

5-1 to the G3 electrode 11 through a stem pin (focus pin) isolated from other stem pins.
A focusing voltage of about 0 kV is applied. An acceleration voltage, which is the highest voltage of about 20 to 30 kV, is applied to the G4 electrode and has the same potential as the shielding cup 13 and the conductive film 5 provided inside the glass envelope 1.

Since the apertures in the central portions of both electrodes constituting the main lens are coaxial, the main lens formed in the center is axially symmetric, and the central beam is focused by the main lens and then along the axis. Go straight on the orbit. On the other hand, the outer holes of both electrodes are off-axis from each other, so that a non-axisymmetric main lens is formed on the outer side. Therefore, the outer beam passes through a part of the main lens region that is deviated in the central beam direction from the central axis of the lens in the divergent lens region formed on the acceleration electrode side, and at the same time as the focusing action by the main lens, Receives concentration in the direction. In this way, the three electron beams are focused on the shadow mask 4 so as to form an image on the shadow mask 4 and at the same time overlap each other.

The operation of concentrating each beam in this way is called static convergence (STC). Further, each electron beam undergoes color selection by the shadow mask 4, and only the component that excites and emits the phosphor on the phosphor screen 3 of the color corresponding to each electron beam passes through the aperture of the shadow mask 4. Then, the fluorescent screen 3 is reached. An external magnetic deflection yoke 14 for scanning the electron beam on the fluorescent screen 3 is also provided.

As described above, by combining the in-line electron gun in which the three electron beam passage holes are arranged on one horizontal plane with the so-called self-convergence deflection yoke that forms a special non-uniform uniform magnetic field distribution, S
It is known that if TC is obtained, convergence can be obtained over the entire area of other screens. However, in general, the self-convergence deflection yoke has a problem that the deflection aberration is large due to the inhomogeneity of the magnetic field and the resolution is lowered in the peripheral portion of the screen.

FIG. 3 schematically shows how the electron beam spot is deformed by the deflection aberration. That is, in the peripheral portion of the screen, the high-intensity portion (core) A of the electron beam indicated by the inclination spreads in the horizontal direction and the low-intensity portion (halo).
B extends vertically.

Conventionally, in order to solve such a problem, the configuration shown in FIG. 4 is known (Japanese Patent Laid-Open No. 61-99249).
Issue).

In the figure, the focusing electrode is divided into two parts, a first member 115 and a second member 116, from the cathode toward the phosphor screen. On the end surface of the first member 115 that faces the second member 116, a slit that is long in the vertical direction is provided as shown in FIG. 4B. As shown in FIG. 4 (c), a slit-shaped opening that is long in the horizontal direction is provided on the end surface of the second member 116 that faces the first member 115, and is synchronized with the deflection current supplied to the deflection yoke. Dynamically changing voltage,
That is, the dynamic voltage is applied by being superimposed on the focusing voltage Vf. When the deflection amount is large, the first member 115
Since the potential difference between the second member 116 and the second member 116 increases, the intensity of the quadrupole lens formed by the slit increases, and a large astigmatism occurs in the electron beam spot. First member 11
If the potential of 5 is higher than that of the second member 116, the astigmatism produced in the electron beam has the effect of extending the core A vertically and the halo B horizontally, so that the electron beam shown in FIG. Astigmatism associated with the deflection can be eliminated, and the resolution of the peripheral portion of the screen can be improved. On the other hand, when the electron beam is not deflected, the first member 1
By eliminating the potential difference between 15 and the second member 116,
Since the condition where astigmatism does not occur in the center of the screen can be achieved by not forming the asymmetric lens, the resolution does not deteriorate.

Further, in the color picture tube, the distance from the main lens to the peripheral portion of the screen is longer than the distance to the central portion of the screen, so that the central and peripheral portions have different electron beam focusing conditions. When the electron beam is focused on the peripheral part, there is a problem that the peripheral part is not focused and the resolution is deteriorated. However, in the conventional example of FIG. 4, since the potential of the second member 116 is increased when the electron beam is deflected to the periphery of the screen, the potential difference from the acceleration voltage of the acceleration electrode 12 is reduced and the lens strength of the main lens is weakened. For this reason, the electron beam focusing point is extended in the screen direction, and the electron beam can be focused on the screen even in the peripheral portion of the screen, and also in this point, deterioration of resolution in the peripheral portion can be prevented. That is, dynamic astigmatism correction and dynamic focus can be realized at the same time.

FIG. 5 shows a configuration showing another conventional example (Japanese Patent Laid-Open No. 61-250933).

As in the case of FIG. 4, focusing electrodes 117, 1
It is divided into two members of 18. As shown in FIGS. 5B and 5C, the plate-shaped correction electrodes 117A and 118A in the vertical and horizontal directions are arranged on the facing surfaces of the respective members so as to be combined with each other to form a quadrupole lens. . Second member 11
8 is a focusing voltage Vf in which the dynamic voltage Vd is superimposed.
Is applied to realize dynamic astigmatism correction and dynamic focus at the same time.

[0017]

However, the electron gun for a picture tube having such a structure has a problem that extremely high precision positioning is required at the time of assembling the same.

That is, vertical and horizontal plate-shaped correction electrodes 117A,
It has been confirmed that when the 118A is combined with each other, if they deviate from the desired positions, a non-uniform force acts on the electron beam during the astigmatism correction to distort the spot on the screen.

Therefore, the present invention has been made under such circumstances, and the object of the present invention is to achieve a highly accurate assembly without requiring a high degree of positioning at the time of assembly. It is to provide an electron gun for a picture tube that can be used.

[0020]

In order to achieve such an object, the present invention basically comprises a cathode, a focusing electrode and an accelerating electrode which are sequentially arranged in the electron beam direction from the cathode. In an electron gun for a picture tube, the focusing electrode is composed of a first member and a second member which are sequentially arranged from the cathode, and a single opening is provided on a surface side of the second member facing the first member. A flat plate electrode electrically connected to the left and right of an electron beam passage hole provided on the surface of the first member facing the second member is extended to the second member through the single opening. In addition to the above structure, a voltage varying in synchronization with the deflection amount of the electron beam is applied to the second member.

[0021]

The electron gun for a picture tube constructed in this manner is an electrode arranged close to the electron beam passage hole in the vicinity of the facing surfaces of the first member and the second member as in the prior art. The electrode portion belonging to the two members does not exist.

[0022] Therefore, a high There accuracy is not be required when combining the first member and the second member to the mutual positional relationship.

[0023] Thus, wear precision assembly us in formed without requiring a high degree of positioning during assembly.

[0024]

FIG. 1 shows an embodiment of the present invention. The focusing electrode is divided into a first member 111 and a second member 112, and the second member 112 is provided with a single laterally long opening on the surface facing the first member 111.

The first member 111 is provided with three circular electron beam passage holes on the surface facing the second member 112, and has a flat plate shape extending in the direction of the second member 112 to the left and right of the electron beam passage holes. The correction electrode 113 is connected.

A plate member 114 having a circular electron beam passage hole is arranged in the second member 112.

A constant focusing voltage Vf is applied to the first member 111.
The dynamic voltage Vd is applied to the second member 112 by superimposing it on Vf. When the electron beam is deflected, Vd is increased with an increase in the deflection amount. As Vd rises, the strength of the quadrupole lens formed at the facing portion of the first member 111 and the second member 112 increases, and astigmatism due to electron beam deflection can be corrected. At the same time, the reduction of the voltage difference between the acceleration voltage Eb of the acceleration electrode 12 and the voltage applied to the second member 112 reduces the strength of the main lens and increases the distance between the main lens and the electron beam focusing point. The electron beam can be focused on the part.

That is, dynamic astigmatism correction and dynamic focusing can be performed at the same time.

Then, as in the prior art, the electrodes arranged in the vicinity of the respective facing surfaces of the first member and the second member in the vicinity of the electron beam passage hole and belonging to the second member (see FIG. 5). (Corresponding to the member denoted by reference numeral 118A) does not exist.

Therefore, when the first member 111 and the second member 112 are combined, the positional relationship between them is as follows.
High accuracy is no longer required.

[0031] Thus, that obtained to achieve assembly of high precision without requiring a high degree of positioning during assembly.

In the embodiment described above, the so-called aperture electrode 114 having a circular electron beam passage hole is arranged inside the second member 112. That is, when the dynamic voltage Vd rises, the voltage is applied to the aperture electrode 114 in the positive direction with respect to the plate-shaped correction electrode 113, and the quadrupole lens strength can be further magnified. Also, if the diameter of the circular electron beam passage hole is made to match the diameter of the cylindrical electrode fixing jig used for assembling the electron gun, the second member can be fixed by this jig, thus improving the assembly accuracy. Can be planned.

In this case, in order to increase the strength of the quadrupole lens, the electron beam passage hole has a laterally long shape rather than a circular shape, and it is not an individual aperture corresponding to each electron beam but an entire electron beam. A common single laterally long aperture may be used.

However, it goes without saying that the aperture electrode 114 does not necessarily have to be arranged for the application of the present invention.

Further, by making the plate-shaped correction electrodes 113 arranged on the left and right of the outer electron beam passage hole different sizes and shapes on the left and right, or by making them different distances from the central axis of the outer electron beam passage hole. The quadrupole lens exerts different effects on the central beam side portion of the outer electron beam and the electrode side wall portion on the opposite side to prevent the electron beam spot on the screen from being distorted. Astigmatism can be properly corrected for each of the beam and the central electron beam.

[0036]

[0037]

As is apparent from the above description,
According to the electron gun for a picture tube according to the present invention, highly accurate assembly can be achieved without requiring high positioning at the time of assembly.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an electron gun for a picture tube according to the present invention, in which (a) is a sectional view and (b) is A- of (a).
It is sectional drawing in the A'line.

FIG. 2 is a sectional view showing an example of a picture tube provided with a conventional electron gun.

FIG. 3 is an explanatory diagram for explaining a core and a halo on an image receiving surface.

4A to 4C are configuration diagrams showing an example of a conventional electron gun.

5A to 5C are configuration diagrams showing another example of a conventional electron gun.

FIG. 6 is an explanatory view showing another embodiment of the picture tube electron gun according to the present invention.

[Explanation of symbols]

111 ... 1st member (focusing electrode), 112 ... 2nd member (focusing electrode), 113 ... Auxiliary electrode.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-2-72546 (JP, A) JP-A-1-137540 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 29/48 H01J 29/50 H01J 29/56

Claims (2)

(57) [Claims] 1. A cathode and a plurality of electron beams are generated,
And a first electrode means for directing the phosphor screen these electron beams along mutually parallel early passage on one plane, before
Serial In electron gun for picture tube and a second electrode means constituting a main lens for focusing the electron beams on the phosphor screen, of the electrodes constituting the main lens, an acceleration electrode applied with the highest voltage adjacent to the focusing electrode is constituted by a first member and a second member which are sequentially disposed on the phosphor screen direction from said cathode, a single aperture in the surface facing the first member of the second member Is provided, and the side parallel to the one plane of the opening is supplemented with a second flat plate.
The first flat plate-shaped correction electrodes electrically connected to the first member are made to function as a positive electrode and are provided on the left and right of the electron beam passage hole provided on the surface of the first member facing the second member. An electron gun for a picture tube, characterized in that the electron gun is configured to extend into a second member through a single opening , and a voltage that fluctuates in synchronization with an amount of deflection of an electron beam is applied to the second member. 2. The picture tube electron gun according to claim 1, wherein a plate-shaped electrode having an electron beam passage hole is arranged inside the second member.