JPH10334825A - Electron gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance resolution over the entire are of a screen. SOLUTION: For instance, a second electrode 2 which serves as an accelerating electrode is structured as 2 separated bodies of divided electrodes 2a, 2b consisting of two cage-type electrodes, and has a quadruple electrode lens construction which produces lens action according to a deflection direction of an electron beam B. The second electrode 2 is placed in the neighborhood of a crossover position, where a beam diameter of an electron beam B emitted from a negative electrode 10 becomes a minimum and forms an object point diameter. Degree of astigmatism of the electron beam B is made variable, and a divergence angle is adjusted by the second electrode 2 placed in the neighborhood of the crossover position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for focusing an electron beam emitted from a cathode by a lens function of a plurality of electrodes.

[0002]

2. Description of the Related Art In a cathode ray tube used for a display device or the like, an electron beam emitted from an electron gun is deflection-controlled by a deflection yoke and impinges on a phosphor screen surface (hereinafter simply referred to as a "fluorescent surface"). To form an image. The resolution characteristic of the image formed here largely depends on the spot shape (including the spot diameter) of the electron beam that collides with the phosphor screen. That is, the smaller the spot diameter of the electron beam and the closer to a perfect circle, the higher the resolution characteristics.

Generally, the trajectory of an electron beam from an electron gun to a fluorescent screen becomes longer as the electron beam deflection angle increases toward the periphery of the fluorescent screen. Therefore, if the focus adjustment is performed on the electron gun so that the spot diameter of the electron beam is small and close to a perfect circle at the center of the phosphor screen, the overfocus state becomes closer to the periphery of the phosphor screen and the resolution is reduced. .

Therefore, in recent years, in order to improve the resolution in the peripheral portion, a quadrupole lens structure that provides a lens action according to the deflection direction of the electron beam is provided in the electron gun so that the focus is concentrated over the entire screen. Various improved electron guns have been developed.

FIG. 12 is a structural view showing a schematic structure of a conventional electron gun employing a quadrupole lens structure. Here, the structure of an electron gun applied to a color cathode ray tube is shown.

As shown in FIG. 12, a conventional electron gun is
A cathode 100 for emitting an electron beam B;
And an electrode group 110 (first to sixth electrodes 101 to 106) including a plurality of electrodes for focusing the electron beam B emitted from the phosphor screen on the phosphor screen.

Here, the cathode 100 is composed of a cathode 100a for a red beam, a cathode 100b for a green beam, and a cathode 100c for a blue beam.

The electrode group 110 includes a control electrode for controlling the path of the electron beam B emitted from the cathode 100, an acceleration electrode for accelerating the electron beam B, an auxiliary electrode for converging the electron beam B, and a converging electrode. , And a final accelerating electrode for finally accelerating the electron beam B. FIG.
In the second example, the first electrode 101 is a control electrode, and the second electrode 101 is a control electrode.
Electrode 102 is an accelerating electrode, and third to fifth electrodes 103
To 105 are auxiliary and focusing electrodes, and the sixth electrode 106
Is the final accelerating electrode. Note that the sixth electrode 106 has
The shield cup 107 is conductively welded.

Here, the fifth electrode 10 as a focusing electrode
5 comprises two housing-type electrodes 105a and 105b,
A quadrupole lens structure that provides a lens action according to the deflection direction of the electron beam B is realized.

The other electrode 105 of the second electrode 102 and the fourth electrode 104, and the third electrode 103 and the fifth electrode 105
The same voltage is applied to each of b.

FIG. 13 is a waveform diagram showing the waveform of the voltage applied to the fifth electrode 105. In FIG. 13, a waveform indicated by reference numeral 131 is a voltage applied to one electrode 105a, and a waveform indicated by 132 is a voltage applied to the other electrode 105b.
Is the voltage applied to.

As shown in FIG. 13, the fifth electrode 105
A fixed voltage is applied to one electrode 105a, and a variable voltage is applied to the other electrode 105b. Here, the variable voltage applied to the other electrode 105b is 3 to 10 [K
V] in synchronization with the deflection cycle of the electron beam B at the medium voltage.
A voltage of 00 to 1500 [V] is superimposed. As described above, by applying the variable voltage synchronized with the deflection cycle of the electron beam B, a lens action corresponding to the deflection direction of the electron beam B can be provided. Note that FIG.
In the portion indicated by symbol T _V is corresponds to one vertical deflection period, the portion indicated by T _H corresponds to one horizontal deflection period. In addition, portions indicated by reference numerals 141, 142, and 143 are respectively a corner portion, a center portion on the screen of the phosphor screen,
It corresponds to the end of the Y axis.

Here, the name of each screen area of the phosphor screen is defined as follows. FIG. 20 is a screen configuration diagram for explaining the screen configuration of the phosphor screen. In FIG. 20, the center area 200 is the center area, and four areas 300 at the corners of the screen are shown.
Is referred to as a corner portion, the area 400 at the upper and lower ends of the screen is referred to as a Y-axis end, and the area 500 at the left and right ends of the screen is referred to as an X-axis end. Further, the screen peripheral portion is used as a generic term for a screen peripheral region including a corner portion, a Y-axis end portion, and an X-axis end portion. In addition,
In FIG. 20, an area indicated by a symbol A indicates a first quadrant of the screen.

Next, the lens operation of the electron gun having the electrode structure shown in FIG. 12 will be described. FIG.
6 is an optical model optically showing a lens action by a conventional electron gun when an electron beam B is deflected to a screen corner. In FIG. 14, the operation of the electron gun in the horizontal direction (H) and the operation in the vertical direction (V) are simultaneously shown. Reference numerals 130 _H and 130 _V in the drawing indicate the trajectories of the electron beam B in the horizontal direction and the vertical direction, respectively. Reference numerals P _H and P _V in the figure indicate the principal point positions of the electron lens in the horizontal and vertical directions, respectively.

First, the function of the lens in the horizontal direction will be described. Electron beam B diverges at a divergence angle alpha _H from the cross-over (intersection) Position O of the electron beam B corresponding to the object point, a convex lens 131 is a horizontal action of the quadrupole lens formed by the fifth electrode 105 _H and the fifth electrode 105
Of the other electrode 105b and the sixth electrode as the final accelerating electrode
A convex lens 132 as a main electron lens formed by the electrode 106 and a concave lens 133 _H formed by a horizontal component of a magnetic field of a deflection yoke (not shown) project on the phosphor screen 500 to form an image. I do. Here, the crossover position O
The phosphor screen 5 the distance from to the principal point P _H a _H, a principal point P _H
When the distance to 00 and b _H, the horizontal direction of the image magnification M _H
Is a b _H / a _H.

Next, the function of the lens in the vertical direction will be described. The electron beam B diverged from the crossover position O at a divergence angle α _V is a concave lens 131 _V that is a vertical action of a quadrupole lens formed by the fifth electrode 105 and the other electrode of the fifth electrode 105. and 105b and final accelerating lens 132 is a main electron lens formed by the sixth electrode 106 as an electrode, are in the phosphor screen 500 through the convex lens 133 _V which is formed by the vertical component of the magnetic field (not shown) deflection yoke Protrude to form an image. Here, distance a _V from the crossover position O to the principal point P _V, and the distance from the principal point P _V to the fluorescent surface 500 and b _V, image magnification M _V in the vertical direction, b _V / a _V Becomes

According to the electron gun using the quadrupole lens as described above, the overfocus state at the peripheral portion of the phosphor screen is improved. However, as shown in FIG. 13, the positions of the main points P _H and P _V in the horizontal direction and the vertical direction in the screen corner portion are the crossover positions O, respectively.
Side, the fluorescent screen 500 side, and a large principal point interval occurs. For this reason, the horizontal image magnification M _H becomes larger than the vertical image magnification M _V, and the spot shape of the electron beam B becomes horizontally long due to this image magnification difference, and the horizontal resolution deteriorates. .

Therefore, the horizontal,
In order to eliminate the difference in image magnification in the vertical direction, a quadrupole lens structure is adopted for the third electrode 103 as well as the fifth electrode 105, and the focus at the center of the screen and the focus at the corner of the screen are simultaneously improved. Electron guns have been proposed (JP-A-7-262935, JP-A-3-93135).

FIG. 15 is a structural view showing a schematic structure of another conventional electron gun employing two quadrupole lens structures.
In the following description, the same components as those of the electron gun shown in FIG. 12 are denoted by the same reference numerals, and description thereof will be omitted.

In the electron gun shown in FIG. 15, the third electrode 1
03 is divided into one electrode 103a and the other electrode 103b similarly to the fifth electrode 105 to realize two quadrupole lens structures. In this electron gun, the second electrode 102 and the fourth electrode 104, one of the third electrodes 103 103 a and the fifth electrode 105 of the other electrode 105.
b, the same voltage is applied to the other electrode 103b of the third electrode 103 and one electrode 105a of the fifth electrode 105, respectively.

FIG. 16 is an optical model optically showing the lens action when the electron beam B is deflected to the screen corner by the electron gun having the structure shown in FIG. Also,
FIG. 17 is an optical model optically showing a lens function when the electron beam B is deflected to the screen Y-axis end. In FIGS. 16 and 17, the horizontal direction (H) of the electron gun is shown.
And the action in the vertical direction (V) at the same time.
Reference numerals 160 _H and 170 _H in the figure indicate the trajectories of the electron beam B in the horizontal direction at the screen corner and the Y-axis end, respectively, and reference numerals 160 _V and 170 _V indicate the screen corner and the Y-axis end, respectively. The trajectory of the electron beam B in the vertical direction of the section is shown. Other symbols are the same as in FIG.

[0022] As shown in these figures, the electron gun having the structure shown in FIG. 15, the lens action in the horizontal direction, in front of the convex lens 131 _H, 4 double pole formed by the third electrode 103 concave lens 134 _H is a horizontal action of the lens have been added. Also, as a vertical lens action,
In front of the concave lens 131 _V, a convex lens 134 is perpendicular action of quadrupole lens formed by the third electrode 103 _V
Has been added.

In the electron gun having the structure shown in FIG.
16 and 17 as compared with the electron gun having the structure shown in FIG.
As shown in the optical model of the above, at the corners of the screen and at the end of the Y-axis, the distance between the principal points in the horizontal and vertical directions is reduced, so that the difference in image magnification is also reduced, and the spot shape of the electron beam B is changed from horizontal to circular. It has been improved to get closer. In this case, the Y-axis end is improved so that the principal point interval is smaller than the screen corner, and the image magnification difference is also smaller.

[0024]

However, FIG.
In the structure of another conventional electron gun as shown in FIG. 2, the arrangement position of the third electrode 103 constituting the quadrupole lens is far from the crossover position O.
The beam diameter becomes large before reaching the electrode 103 of, and the state is susceptible to aberration. For this reason, there has been a problem that the degree of improvement of the spot shape at the screen corner portion is small and the effect is insufficient.

Further, as shown in FIG. 17, at the end of the Y-axis, due to the action of the quadrupole lens of the third electrode 103, the image magnification does not become horizontally long, but as shown in FIG. Since the beam incident angle β _Y becomes an acute angle when entering the end of the Y-axis of the phosphor screen 500, the spot diameter d of the electron beam B
There is a problem in that _Y becomes larger than the beam diameter d (for example, about 1.25 times), and the spot shape becomes vertically long.

For this reason, there is a problem that the vertical resolution at the end of the Y-axis deteriorates, and the effect of improving the focus uniformity of the entire screen is small. Here, FIG. 19 shows a spot shape of the electron beam B in the first quadrant (see FIG. 20) of the screen. As shown in FIG. 19, in the conventional electron gun, the shape of the spot 191 on the screen center part but circular, the shape of the spot 191 _Y in Y-axis end portion becomes vertically long. Also,
Spots 191 _C and 191 at corners and X-axis end
Is oblong.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an electron gun capable of increasing the resolution over the entire screen.

[0028]

An electron gun according to the present invention comprises:
In the vicinity of the crossover position where the beam diameter of the electron beam emitted from the cathode is minimized, a two-piece split electrode that provides a different lens action according to the deflection of the electron beam is provided.

In the electron gun according to the present invention, the two-piece split electrode is provided in the vicinity of the crossover position, so that the electron beam emitted from the cathode has a different lens action according to the deflection of the electron beam.

[0030]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, the names of the respective screen regions on the phosphor screen are the same as those described with reference to FIG. 20 in the section of the related art.

[First Embodiment] First, the first embodiment of the present invention will be described.
An embodiment will be described. FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a structural diagram showing a schematic structure of an electron gun according to the embodiment. Here, the structure of an electron gun applied to a color cathode ray tube is shown.

As shown in FIG. 1, the electron gun according to the present embodiment has a cathode 10 for emitting an electron beam B and a plurality of beams for focusing the electron beam B emitted from the cathode 10 on a phosphor screen. And an electrode group 11 (first to sixth electrodes 1 to 6) including the above electrodes.

Here, the cathode 10 comprises a red beam cathode 10a, a green beam cathode 10b, and a blue beam cathode 10c.

The electrode group 11 includes a control electrode for controlling the path of the electron beam B emitted from the cathode 10, an acceleration electrode for accelerating the electron beam B, an auxiliary electrode for converging the electron beam B, and a converging electrode. , And a final accelerating electrode for finally accelerating the electron beam B. For example,
The first electrode 1 is a control electrode, the second electrode 2 is an acceleration electrode, the third to fifth electrodes 3 to 5 are auxiliary and focusing electrodes, and the sixth electrode 6 is a final acceleration electrode. The sixth
A shield cup 7 is conductively welded to the electrode 6.

Here, for example, the second electrode 2 serving as an accelerating electrode is composed of two divided electrodes 2a and 2b composed of two housing-type electrodes, and functions as a lens according to the deflection direction of the electron beam B. Is realized. The second electrode 2 is disposed in the vicinity of a crossover position (for example, immediately after the crossover position) where the beam diameter of the electron beam B emitted from the cathode 10 becomes minimum and the object diameter is formed.

The fifth electrode 5 as a focusing electrode is also divided into two housing-type divided electrodes 5a and 5b similarly to the second electrode 2.
To realize a quadrupole lens structure that provides a lens action according to the deflection direction of the electron beam B.

One divided electrode 2a of the second electrode 2 and the fourth
The same voltage is applied to each of the electrode 4, the third electrode 3, and one of the divided electrodes 5a of the fifth electrode 5. In addition, the other divided electrode 5b of the fifth electrode 5 has the reference numeral 1 described in the section of the prior art with reference to FIG.
A variable voltage similar to the waveform indicated by 32 is applied.

One divided electrode 2a of the second electrode 2 has:
For example, a fixed voltage of 100 to 900 [V] is applied.
A variable voltage that changes according to the deflection cycle of the electron beam B is applied to the other split electrode 2b. However, the value of the voltage applied to the other divided electrode 2b is a voltage substantially close to the voltage applied to the one divided electrode 2a.

FIGS. 2 and 3 are voltage waveform diagrams showing an example of the voltage applied to the second electrode 2. FIG. In FIGS. 2 and 3, the waveform indicated by reference numeral V ₁ is
a fixed voltage applied to a, a variable voltage waveform indicated by symbol V ₂ is applied to the other divided electrode 2b. FIG. 2 shows a waveform when a variable voltage synchronized with both horizontal deflection and vertical deflection is applied, and FIG. 3 shows a waveform when a variable voltage synchronized with only horizontal deflection is applied. I have.

As shown in FIGS. 2 and 3, by applying a variable voltage in synchronization with the deflection cycle of the electron beam B, a lens action corresponding to the deflection direction of the electron beam B can be provided. In FIGS. 2 and 3,
Portion indicated by symbol T _V is corresponds to one vertical deflection period, the portion indicated by T _H corresponds to one horizontal deflection period. In FIG. 2, portions indicated by reference numerals 41, 42, and 43 respectively correspond to a corner portion, a center portion, and a Y-axis end portion on the screen of the phosphor screen. In the case of FIG. 2, one divided electrode 2a of the second electrode 2 and the other divided electrode 2b have the same voltage in the screen center portion.

Here, the other divided electrode 2 of the second electrode 2
If the variable voltage applied to b has a waveform as shown in FIG. 3, it does not work for vertical deflection, so that the spot shape at the end of the Y-axis does not become vertically long, and the resolution in the vertical direction is lower than that of the conventional electron beam. It can be made not to deteriorate as much as a gun. Also, assuming that the variable voltage applied to the other split electrode 2b is in the opposite direction between the horizontal deflection and the vertical deflection as shown in the waveform of FIG.
It is possible to make the spot shape at the end of the Y axis horizontally long. As described above, by adjusting the variable voltage applied to the other split electrode 2b, the electron beam B can be independently optimized according to the deflection direction of the electron beam B, and the screen center section, the screen corner section, Electron beam B at each end of Y axis
Can be made smaller.

Next, the structure of the electron beam passage hole of the second electrode 2 will be described. One of the divided electrodes 2a of the second electrode 2 is provided with a non-circular electron beam passage hole having a long axis in the horizontal or vertical direction. The other divided electrode 2b is provided with a non-circular electron beam passage hole having a major axis in a direction orthogonal to the major axis of the electron beam passage hole provided in the one divided electrode 2b.

FIGS. 4 and 5 are front views showing an example of the structure of the electron beam passage hole of the second electrode 2. FIG. In these drawings, (a) shows a state in which one of the split electrodes 2a of the second electrode 2 is viewed from the third electrode 3 side.
(B) shows a state where the other split electrode 2b is viewed from the first electrode 1 side.

As shown in FIG. 4 and FIG. 5, the electron beam passage hole provided in the second electrode 2 is formed in, for example, a rectangular or oval (elliptical or the like) hole shape.
Three holes are arranged in parallel corresponding to the three electron beams B for color emitted from Oa to 10c. Here, when the hole shape is rectangular, as shown in FIG. 4A, one of the divided electrodes 2a of the second electrode 2 is a vertically long rectangular hole 52a having a long axis in the vertical direction. The other split electrode 2
As shown in FIG. 4B, b is a horizontally long rectangular hole 62a having a long axis in the horizontal direction. When the shape of the hole is an ellipse or the like, as shown in FIG.
One of the divided electrodes 2a of the electrode 2 is a vertically long oval hole 52b having a long axis in the vertical direction, and the other divided electrode 2b is formed as shown in FIG.
As shown in (b), it is a horizontally long oval hole 62b having a long axis in the horizontal direction.

Incidentally, as the structure of the electron beam passage hole of the second electrode 2, the electrode may be partially thinned to have a structure corresponding to the above-mentioned rectangular or oval hole. FIG.
FIG. 9 is a front view showing another example of the hole shape of the second electrode 2.

As shown in FIG. 6, the structure of the electron beam passage hole of the second electrode 2 is such that both the divided electrode 2a and the other divided electrode 2b are circular holes 52c and 62c, and the circular holes 52c and 62c are formed. Around the area 14a, 1
4b. At this time, the circular hole 5
The area 14a around 2c is vertically elongated, and the area 14b around the circular hole 62c is horizontally elongated.

By using the second electrode 2 having the above configuration, the astigmatism between the second electrodes can be changed in synchronization with the deflection of the electron beam B on the screen. In particular, the divergence angle of the electron beam B at the crossover position as an object point can be changed according to the deflection of the electron beam B.

FIG. 7 is an optical model optically showing a lens action when the electron beam B is deflected to the screen corner by the electron gun according to the present embodiment. In FIG. 7, the operation of the electron gun in the horizontal direction (H) and the operation in the vertical direction (V) are simultaneously shown. Reference numerals 70 _H and 70 _V in the figure indicate the trajectories of the electron beam B in the horizontal and vertical directions, respectively. Reference numerals P _H and P _V in the figure indicate the principal point positions of the electron lens in the horizontal and vertical directions, respectively.

First, the function of the lens in the horizontal direction will be described. An electron beam B diverged from the crossover position O of the electron beam B corresponding to the object point at a divergence angle θ _H is a convex lens 31 _H which is a horizontal action of a quadrupole lens formed by the fifth electrode 5, and A convex lens 32 as a main electron lens formed by the other electrode 5b of the fifth electrode 5 and a sixth electrode 6 as a final acceleration electrode, and a deflection yoke (not shown)
And projecting on the phosphor screen 50 through the concave lens 33 _H formed by the horizontal component of the magnetic field to form an image. Here, the distance from the crossover position O to the principal point P _H is a _H , and the principal point P _H
Assuming that the distance from _H to the fluorescent screen 50 is b _H , the horizontal image magnification M _H is b _H / a _H.

Next, the function of the lens in the vertical direction will be described. The electron beam B diverging from the crossover position O at a divergence angle θ _V is converted into a concave lens 31 _V which is a vertical action of a quadrupole lens formed by the fifth electrode 5 and a fifth electrode 5
A convex lens 32, which is a main electron lens formed by the other electrode 5b and the sixth electrode 6 as a final acceleration electrode;
An image is formed by projecting on the phosphor screen 50 via a convex lens 33 _V formed by a vertical component of a magnetic field of a deflection yoke (not shown). Here, the distance of the distance from the crossover position O to the principal point P _V a _V, from the principal point P _V to the fluorescent surface 50 b
When is _V, image magnification M _V in the vertical direction becomes b _V / a _V.

As shown by the optical model, in the electron gun according to the present embodiment, the positions of the principal points P _H and P _V in the horizontal and vertical directions are respectively set at the crossover position O at the screen corner. , To the side of the phosphor screen 50, and a large interval between principal points occurs. Therefore, in terms of image magnification, the image magnification M _H in the horizontal direction is larger than the image magnification M _{V in the} vertical direction. However, the divergence angle of the electron beam B from the crossover position O as the object point is such that the divergence angle θ _{H in} the horizontal direction is larger than the divergence angle in the vertical direction due to the effect of changing the astigmatism of the second electrode 2. The beam diameter larger than the angle θ _V and corresponding to the horizontal object point diameter becomes smaller. As a result, the spot shape of the electron beam B at the corner of the screen becomes close to a circle.

FIG. 8 shows a spot shape of the electron beam B focused by the electron gun according to the present embodiment. FIG. 8 shows the first quadrant of the screen (see FIG. 20). As shown in this figure, the electron gun according to the present embodiment, the shape of the spot 81 at the screen center portion is circular, are approximately circular shape of the spot 81 _Y in the Y-axis end. The spots 81 _C and 81 _X at the corners and the X-axis end are also closer to a circle than the conventional electron gun.

As described above, according to the electron gun according to the present embodiment, the second electrode 2 is positioned immediately after the crossover position O where the beam diameter of the electron beam B is small and the second electrode 2 is less susceptible to aberration. The astigmatism of the electron beam B is made variable to adjust the divergence angle. For this reason, it is possible to control the focus over the entire screen by reducing the deterioration sensitivity of the spot and increasing the correction effect. Accordingly, the spot diameter of the electron beam B is small and close to a perfect circle over the entire area of the phosphor screen, and the resolution can be increased over the entire screen.

[Second Embodiment] Next, a second embodiment of the present invention will be described.
An embodiment will be described. In the following description, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 9 is a front view showing an example of the hole shape of the electron beam passage hole of the second electrode 2 in the electron gun according to the present embodiment. Note that, in FIG. 9, (a)
3 shows a state in which one of the divided electrodes 2a of the electrode 2 is viewed from the third electrode 3 side, and FIG. 4B shows a state in which the other divided electrode 2b is viewed from the first electrode 1 side. .

As shown in FIG. 9, in this embodiment, as the electron beam passage holes of the second electrode 2, circular holes having different sizes from one divided electrode 2a and the other divided electrode 2b are used. 52d and 62d are provided. FIG.
In the example, the circular hole 62d has a larger circular shape than the circular hole 52d.

Circular holes 52d of such different sizes are provided.
According to 62d, the astigmatism of the electron beam B at the crossover position cannot be made variable as in the first embodiment, but the divergence angle of the electron beam B can be controlled more accurately. Become.

FIG. 10 is an optical model optically showing a lens action when the electron beam B is deflected to the center of the screen by the electron gun according to the second embodiment of the present invention. FIG. 10 simultaneously shows the operation of the electron gun in the horizontal direction (H) and the operation in the vertical direction (V).

At the center of the screen, the lens action of the electron gun is substantially the same in both the horizontal and vertical directions.
The electron beam B diverged from the crossover position O of the electron beam B at the divergence angle θ is the other electrode 5 b of the fifth electrode 5.
The light is focused on the phosphor screen 50 by the convex lens 32 which is the main electron lens formed by the sixth electrode 6 as the final acceleration electrode.

In the electron gun according to the present embodiment, it is possible to increase the divergence angle θ and reduce the spot diameter at the center of the screen. Further, for example, the divergence angle at the peripheral portion of the screen can be more accurately suppressed, the sensitivity of spot deterioration can be reduced, and the variation of the spot of the electron beam B at the peripheral portion of the screen can be suppressed.

As described above, according to the electron gun of the present embodiment, the electron beam B emitted from the cathode 10
Can accurately control the divergence angle of the electron beam B with the second electrode 2 immediately after forming the object diameter at the crossover position,
As in the first embodiment, it is possible to increase the resolution over the entire screen.

The present invention is not limited to the above embodiments, and various modifications can be made. For example, one split electrode 2a and the other split electrode 2b of the second electrode 2
The position of the phosphor screen at the same voltage on the screen does not need to be at the screen center, but may be at the periphery of the screen. Further, it is not always necessary to provide a place where the voltage between the two electrodes becomes the same voltage.

Further, in the above-described embodiment, the example in which the voltage having the waveform shown in FIGS. 2 and 3 is applied to the second electrode 2 has been described. However, the waveform shape shown in FIGS. It may be applied in the opposite direction. in this case,
Since the force acting between the second electrodes 2 is reversed, the direction of the long axis of the passage hole of the electron beam B shown in FIGS. 4 to 6 is reversed between the one divided electrode 2a and the other divided electrode 2b. By doing so, the same effect as in the above embodiment can be obtained.

Further, in the above embodiment, the second electrode 2
The third electrode 3 is divided into two divided electrodes 3a and 3b as shown in the structural view of the electron gun in FIG.
May be integrated into two. In this case, the divided electrodes 3a, 3
A voltage having a waveform as shown in FIGS. 2 and 3 is applied to either one of b.

In the above embodiment, the electrodes have a six-pole structure. However, a smaller or larger number of electrode structures may be used.

[0066]

As described above, claims 1 to 6
According to the electron gun described in any of the above, the split electrode provided near the crossover position provides a different lens action according to the deflection of the electron beam, so that the electron beam is deflected at a stage that is not easily affected by aberration. The divergence angle of the electron beam can be adjusted according to the direction. For example, the diameter of the electron beam can be reduced so that the focus deterioration sensitivity at the peripheral portion of the screen is reduced. This makes it possible to suppress variations in spot shape at the periphery of the screen, and to increase the resolution over the entire screen.

Further, according to the electron gun of the second aspect,
A fixed voltage is applied to one of the divided electrodes, and a variable voltage is applied to the other divided electrode in accordance with the deflection cycle of the electron beam. Thus, the voltage can be freely set and applied to the divided electrode, and the focus state over the entire screen can be further improved.

According to the electron gun of the third aspect,
Since each of the divided electrodes is provided with a non-circular electron beam passage hole having a long axis orthogonal to each other, in addition to the effect of the electron gun according to claim 1, the astigmatism of the electron beam B is variably diverged. There is an effect that the angle can be adjusted.

According to the electron gun of the fourth aspect,
By providing a thin region around the electron beam passage hole so that each of the divided electrodes has a long axis in a direction orthogonal to each other, an effect equivalent to that of the electron gun according to the third aspect can be obtained.

According to the electron gun of the fifth aspect,
Since each divided electrode is provided with an electron beam passage hole having a different size, an effect that the divergence angle of the electron beam B can be more accurately adjusted in addition to the effect of the electron gun according to claim 1. Play.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing a schematic structure of an electron gun according to a first embodiment of the present invention.

FIG. 2 shows a second example of the electron gun according to the first embodiment of the present invention.
FIG. 4 is a waveform diagram showing a waveform of a voltage applied to the electrode of FIG.

FIG. 3 shows a second example of the electron gun according to the first embodiment of the present invention.
FIG. 4 is a waveform diagram showing a waveform of a voltage applied to the electrode of FIG.

FIG. 4 shows a second example of the electron gun according to the first embodiment of the present invention.
FIG. 2 is a front view showing an example of the structure of the electrode.

FIG. 5 shows a second example of the electron gun according to the first embodiment of the present invention.
FIG. 7 is a front view showing another example of the electrode structure.

FIG. 6 shows a second example of the electron gun according to the first embodiment of the present invention.
It is a front view which shows another example of the structure of the electrode of this.

FIG. 7 is an optical model optically showing a lens action of an electron gun when an electron beam is deflected to a screen corner.

FIG. 8 is a spot diagram showing a spot shape of an electron beam formed by the electron gun according to the first embodiment of the present invention.

FIG. 9 shows a second example of the electron gun according to the second embodiment of the present invention.
It is a front view which shows the structure of the electrode of FIG.

FIG. 10 is an optical model optically showing a lens action of an electron gun when an electron beam is deflected to a screen center.

FIG. 11 is a structural diagram showing a schematic structure of an electron gun according to another embodiment of the present invention.

FIG. 12 is a structural diagram showing a schematic structure of a conventional electron gun.

FIG. 13 is a waveform diagram showing a waveform of a voltage applied to a fifth electrode of a conventional electron gun.

FIG. 14 is an optical model optically showing a lens action of a conventional electron gun when an electron beam is deflected to a screen corner.

FIG. 15 is a structural view showing a schematic structure of another conventional electron gun.

FIG. 16 is an optical model optically showing a lens action of another conventional electron gun when an electron beam is deflected to a screen corner.

FIG. 17 is an optical model optically showing a lens action of another conventional electron gun when an electron beam is deflected to a screen Y-axis end;

FIG. 18 is an explanatory diagram for explaining a spot shape of an electron beam formed by another conventional electron gun.

FIG. 19 is a spot diagram showing a spot shape of an electron beam formed by another conventional electron gun.

FIG. 20 is a screen configuration diagram for describing a screen configuration on a phosphor screen.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st electrode, 2 ... 2nd electrode, 2a ... One divided electrode, 2b ... The other divided electrode, 3 ... 3rd electrode, 4 ... 4th electrode, 5 ... 5th electrode, 6 ... Sixth electrode, 10 ... Cathode, 11 ... Electrode group, B ... Electron beam

Claims (6)

[Claims] 1. An electron gun for emitting an electron beam used for deflection control from a cathode and converging by a lens action by a plurality of electrodes, wherein a crossover position at which a beam diameter of the electron beam emitted from the cathode is minimized. An electron gun, wherein a divided electrode is provided in the vicinity, which has a different lens function according to the deflection of the electron beam. 2. The two-piece split electrode includes one split electrode to which a fixed voltage is applied and the other split electrode to which a variable voltage that changes according to a deflection cycle of the electron beam is applied. The electron gun according to claim 1, wherein: 3. A non-circular electron beam passage hole having a major axis in a horizontal or vertical direction is provided in one of the divided electrodes, and the other divided electrode has an electron beam passing through the one divided electrode. 3. The electron gun according to claim 2, wherein a non-circular electron beam passage hole having a major axis in a direction orthogonal to the major axis of the hole is provided. 4. A thin region is provided around each of the one divided electrode and the other divided electrode around the electron beam passage hole so as to have a long axis in a direction orthogonal to each other. Item 2. The electron gun according to Item 2. 5. The electron gun according to claim 2, wherein the one divided electrode and the other divided electrode are provided with electron beam passage holes having different sizes. 6. The electron gun according to claim 1, wherein said two-piece split electrode is an acceleration electrode for accelerating said electron beam.