JPH1012156A - Cathode ray tube - Google Patents

Abstract

(57) [Problem] To provide a cathode ray tube capable of reducing variation in resolution over the entire screen and optimizing uniformity of a beam spot. SOLUTION: Cathode K and first to sixth grids
In the cathode ray tube provided with the electron gun 16 composed of G1 to G6, the fourth grid G4 is divided into at least two electrode elements G41 and G42, at least one of which is connected to the second grid G2, and other electrode elements are connected. Is connected to the second grid via a resistor 19 and grounded via a variable resistor 20. The electrode element has astigmatism in which the focusing power in the horizontal direction is different from the focusing power in the vertical direction. The astigmatism is such that the focusing power in the horizontal direction is stronger than that in the direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube having an electron gun capable of obtaining a high resolution over the entire phosphor screen.

[0002]

2. Description of the Related Art Generally, a cathode ray tube deflects an electron beam emitted from an electron gun by horizontal and vertical magnetic fields generated by a deflecting device, and horizontally and vertically scans a phosphor screen through a shadow mask. It is formed in a structure for displaying an image on a phosphor screen. In particular, for a color cathode ray tube, the electron gun is an in-line type that emits three electron beams arranged in a line passing on the same horizontal plane, and the three electron beams emitted from the electron gun are converted into a pincushion type shown in FIG. A self-convergence in-line color cathode ray tube concentrated on a phosphor screen by deflecting by a non-uniform magnetic field consisting of a horizontal deflection magnetic field 1H and a barrel-type vertical deflection magnetic field 1V shown in FIG. Has become mainstream.

In the above color cathode ray tube, the following two aberrations (deflection aberrations) are problematic.

One is that the magnetic field generated by the deflection device is
Pin cushion type horizontal deflection magnetic field 1H, vertical deflection magnetic field 1
This is an aberration caused by a non-uniform magnetic field in which V is a barrel shape. The electron beam deflected to the peripheral portion of the phosphor screen due to this aberration is diverged in the horizontal direction to be in an underfocus state, and is focused in the vertical direction to be in an overfocus state.

[0005] The other is aberration caused by the fact that the distance from the electron gun to the phosphor screen increases with the deflection of the electron beam. Due to this aberration, the beam spot at the peripheral portion of the phosphor screen is overfocused in both the horizontal and vertical directions.

Therefore, when the beam spot at the center of the screen is made a perfect circle due to the above two aberrations, the beam spot at the peripheral portion is distorted as shown in FIG. That is, in the horizontal direction (H-axis direction), the underfocus due to the divergent action of the non-uniform magnetic field and the overfocus due to the increase in the distance from the electron gun to the phosphor screen are compensated, but in the vertical direction (V-axis direction). In this case, a remarkable overfocus state is caused by the overfocus due to the focusing action of the non-uniform magnetic field and the overfocus due to the increase in the distance from the electron gun to the phosphor screen. As a result, astigmatism occurs in the horizontal and vertical directions, and the beam spot 2 at the peripheral portion of the screen is distorted into a non-circular shape including a high-brightness core portion 3 and a low-brightness halo portion 4 generated in the vertical direction.
Degrades the resolution of the peripheral part of the screen significantly.

As an electron gun which corrects the shape of the beam spot 2 which degrades the resolution at the peripheral portion of the screen and makes the shape of the beam spot 2 over the entire screen uniform, there is a quadrapotential type electron gun shown in FIG. . This electron gun has three cathodes K arranged in a line in the horizontal direction, three heaters (not shown) for heating these cathodes K separately, and a third cathode K arranged in the direction of the phosphor screen in order from the cathode K. The second grid G2 is connected to the fourth grid G4, and the third grid G3 is connected to the fifth grid G5.

In this electron gun, the first and second grids G1 and G2 are each composed of an integrated plate electrode, and the third to sixth grids G3 to G6 are each composed of an integrated cylindrical electrode. In each of these electrodes, three electron beam passage holes are formed in one row in the horizontal direction corresponding to the three cathodes K, respectively. The first to fourth
The electron beam passage holes on the grids G1 to G4, the fourth grid G4 side of the fifth grid G5, and the phosphor screen side of the sixth grid G6 are perfect circles, but the fifth grid G5.
The electron beam passage holes on the sixth grid G6 side and the fifth grid G5 side of the sixth grid G6 are vertically elongated holes having a slightly larger vertical diameter than the horizontal diameter.

In this electron gun, a cathode K and first to third grids G1 to G1 adjacent to the cathode K are sequentially arranged.
3 form a triode for generating and controlling an electron beam. Third to fifth grids G3 to G5 form a sub-lens for preliminary focusing of the electron beam generated and controlled in the triode. The sixth grids G5 and G6 form a main lens for finally focusing the electron beam prefocused by the sub-lens on the phosphor screen.

[0010] In this case, in the triode and the sub lens,
Since the electron beam passing holes of the electrodes constituting them are all circular, they receive the same focusing action in both the horizontal and vertical directions. However, in the main lens, the sixth grid G6 side of the fifth grid G5 and the sixth grid G6 have the same focusing action. Since the electron beam passage holes on the 5-grid G5 side are both vertically long holes having a vertical diameter larger than the horizontal diameter, astigmatism having a larger focusing effect in the horizontal direction than in the vertical direction occurs.

Considering the focus voltage in the horizontal and vertical directions of the beam spot on the screen of a color cathode ray tube having such an electron gun, the horizontal direction of the beam spot indicates that the non-uniform magnetic field generated by the deflecting device. Since the underfocus due to the divergent action and the overfocus due to the increase in the distance from the electron gun to the phosphor screen are compensated, the focus voltage is substantially the same at the center and the periphery of the screen. On the other hand, in the vertical direction, the focus voltage at the center of the screen is the vertical focus voltage due to the astigmatism of the main lens.
It becomes lower than the horizontal focus voltage. However, in the peripheral part of the screen, the focusing action by the non-uniform magnetic field and the overfocus due to the increase in the distance from the electron gun to the phosphor screen are extremely overfocused, and become higher than the horizontal focus voltage. However, the degree is reduced by the astigmatism of the main lens.

That is, in the above-mentioned electron gun, the focus voltage is adjusted to the horizontal focus voltage,
At the center of the screen, the beam spot becomes slightly longer,
It is possible to reduce a significant overfocus in the vertical direction at the periphery of the screen, and to greatly improve the uniformity of the beam spot over the entire screen.

However, when the electron gun is constructed as described above,
The following problems arise.

In general, the amount of astigmatism varies depending on the size and deflection angle of a cathode ray tube. However, the horizontal focus voltage is smaller than the vertical focus voltage due to the horizontal and vertical focus voltage differences. About 200 ~
It is set to be higher by 1000V. Therefore, in order to obtain the above astigmatism, it is only necessary to make the vertical diameter of the electron beam passage hole of the electrode constituting the main lens about several tens to 100 μm larger than the horizontal diameter. The sensitivity of astigmatism to the difference from the direction diameter is extremely high.

Therefore, in the above-mentioned electron gun, when the accuracy of the electrodes and the assembling accuracy vary and the astigmatism becomes larger than the desired astigmatism, the vertical diameter of the beam spot at the center of the screen is reduced. It becomes extremely large, and the resolution at the center of the screen deteriorates significantly. Conversely, when the astigmatism becomes smaller than the desired astigmatism, the vertical diameter of the beam spot at the peripheral portion of the screen becomes extremely large, and the resolution at the peripheral portion of the screen deteriorates significantly.

In particular, in the case where the size and deflection angle of the cathode ray tube are large or a display tube which requires high resolution, it is difficult to adjust the astigmatism of the main lens. If it varies,
Focus characteristics change significantly. In addition, the occurrence rate of focus defects increases, and productivity is significantly impaired.

[0017]

As described above, the electron beam passing through the fifth and sixth grids constituting the main lens is used as an electron gun for improving the resolution over the entire screen of a self-convergence in-line type color cathode ray tube. There is a quadrapotential type electron gun in which the hole is vertically elongated slightly longer in the vertical direction than in the horizontal direction. However, if the electron gun is simply configured as described above, the sensitivity of astigmatism to the difference between the vertical diameter and the horizontal diameter of the electron beam passage holes of the fifth and sixth grids is extremely high. Astigmatism fluctuates due to variations in accuracy and assembly accuracy, and the vertical diameter of the beam spot at the center of the screen becomes extremely large, and the vertical diameter of the beam spot at the periphery of the screen becomes extremely large, resulting in poor focus characteristics. It changes greatly. In addition, there is a problem that the occurrence rate of focus defects increases, and productivity is significantly impaired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a cathode ray tube capable of reducing variation in resolution over the entire screen and optimizing beam spot uniformity. With the goal.

[0019]

The present invention has a cathode and first to sixth grids sequentially arranged in the direction of the phosphor screen from the cathode, and generates and controls an electron beam by the cathode and the first to third grids. Pole part, third
Sub-lenses for pre-focusing the electron beam generated and controlled by the triode by the fifth to fifth grids, fifth and sixth sub-lenses
The fourth grid is divided into at least two electrode elements in a cathode ray tube provided with an electron gun in which a main lens for finally focusing the electron beam pre-focused by the sub-lens on the phosphor screen by the grid is formed. Connecting at least one of the electrode elements to the second grid, connecting the other electrode elements to the second grid via a resistor, and grounding via a variable resistor; The horizontal and vertical focusing powers have different astigmatisms, and the electron gun as a whole has astigmatism that the horizontal focusing power is stronger than the vertical focusing power.

Further, the main lens has astigmatism in which the focusing power in the horizontal direction is stronger than that in the vertical direction, and an electron lens for compensating the astigmatism of the main lens is formed by the divided electrode elements of the fourth grid. I did it.

Further, the sub-lens has astigmatism having a stronger focusing power in the horizontal direction than in the vertical direction, and an electron lens for compensating the astigmatism of the sub-lens is formed by the divided electrode elements of the fourth grid. I did it.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows an in-line type color cathode ray tube which is one embodiment of the present invention. This color cathode ray tube is a panel 10
And a funnel 1 integrally joined to the panel 10.
1 having an envelope formed on the inner surface of the panel 10;
A phosphor screen 12 composed of a striped three-color phosphor layer that emits blue, green, and red light is provided. Opposed to the phosphor screen 12, a shadow having a number of electron beam passage holes formed therein is provided. A mask 13 is provided. On the other hand, in the neck 14 of the funnel 11, the three electron beams 1 arranged in a line composed of a center beam 15G and a pair of side beams 15B and 15R passing on the same horizontal plane.
An electron gun 16 for emitting 5B, 15G, 15R is provided. The three electron beams 15B, 15G, and 15R emitted from the electron gun 16 are deflected by the horizontal and vertical magnetic fields generated by the deflecting device 17 mounted on the outside of the funnel 11, and the phosphor screen 12 is horizontally and vertically polarized. It is formed in a structure for displaying a color image by performing vertical scanning.

As shown in FIG. 1, the electron gun 16 has three cathodes K arranged in a row in the horizontal direction (H-axis direction), and three heaters (not shown) for heating these cathodes K individually. ), First to sixth grids G1 to G6 sequentially arranged in the direction of the phosphor screen from the cathode K, and the fourth grid G4 is connected to the first electrode element G41 and the fifth grid G4 located on the third grid G3 side. It is divided into two parts: a second electrode element G42 located on the grid G5 side. The second grid G2 and the first electrode element G41, and the third grid G3 and the fifth grid G5 are connected in the tube. Further, the second electrode element G42 is
A resistor 19 of about 10 MΩ arranged in the tube close to 6
, And to the second grid G2 via the resistor 19. One end of the resistor 19 is grounded via a variable resistor 20 of 0 to 20 MΩ disposed outside the tube.

The first and second grids G1 and G2 are each composed of a plate-like electrode having an integrated structure, and the third grid G
3. The two electrode elements G41 and G42 of the fourth grid G4 and the fifth and sixth grids G5 and G6 are each composed of a cylindrical electrode having an integrated structure. Each of these electrodes has 3
Three electron beam passage holes are formed in a row in the horizontal direction corresponding to the cathodes K. The first, second, and third grids G1, G2, G3, the first electrode element G41
The electron beam passage holes on the third grid G3 side, the fifth grid G5 side of the second electrode element G42, and the phosphor screen side of the sixth grid G6 are formed in perfect circles. On the other hand, as shown for the first electrode element G41 in FIG.
The electron beam passage holes 22 on the second electrode element side of the first electrode element G41 and the first electrode element side of the second electrode element G42 have a diameter in the horizontal direction (H-axis direction) larger than that in the vertical direction (V-axis direction). It is a large horizontal hole. FIG. 3 shows the fifth grid G
As shown in FIG. 5, the electron beam passage holes 23 on the sixth grid side of the fifth grid G5 and on the fifth grid side of the sixth grid G6 have a diameter in the vertical direction larger than that in the horizontal direction, and are shown in FIG. It is a vertically long hole that is longer than the conventional electron gun. In this electron gun 16, the cathode K
The first to third grids G1 to G3 sequentially adjacent to the cathode K form a triode for controlling electron emission from the cathode K and forming an electron beam.
The fifth to sixth grids G3 to G5 form a sub-lens for pre-focusing the electron beam controlled and formed by the triode, and the fifth and sixth grids G5 and G6 pre-focus the electron beam. A main lens is formed which ultimately focuses the electron beam on the phosphor screen.

In this case, a voltage lower than that of the first electrode element G41 is applied to the second electrode element G42 of the fourth grid G4. For example, when the applied voltage of the second grid G2 is 900 V
And the resistance value of the variable resistor 20 disposed outside the tube is 0Ω.
/ 10 MΩ / 20 MΩ, the second grid G2
And the voltage of the second electrode element G42 is 0 V / 450 V / 600 V, respectively, with respect to the first electrode element G 41 to which the same voltage of 900 V is applied. Due to the voltage difference between the first electrode element G41 and the second electrode element G42, an electron lens is formed between the first and second electrode elements G41 and G42. This electron lens is a quadrupole lens having astigmatism in which focusing in the vertical direction is stronger than in the horizontal direction because the electron beam passage holes on the opposing surfaces of the electrode elements G41 and G42 are horizontally long. In addition, this quadrupole lens can change the resistance value of the variable resistor 20 so that the second electrode element G42
, The lens intensity (astigmatism) can be adjusted.

On the other hand, in the main lens, the fifth and sixth grids G5 and G6 forming the main lens have vertically elongated electron beam passage holes on the opposing surfaces.
Between the sixth grids G5 and G6, an electron lens having astigmatism having a stronger focusing action in the horizontal direction than in the vertical direction is formed. Moreover, the astigmatism is reduced by making the electron beam passage holes on the opposing surfaces of the fifth and sixth grids G5 and G6 vertically longer than the conventional electron gun.
The astigmatism formed between the first and second electrode elements G41 and G42 of the grid G4 can be made larger.

The fifth and sixth grids G5, G6
When the resistance value of the variable resistor 20 is set to a predetermined intermediate value, the electron beam passage holes on each of the opposed surfaces have astigmatism in which the electron gun 16 as a whole has a stronger focusing action in the horizontal direction than in the vertical direction. , The amount of which is set to be similar to that of a conventional electron gun.

When the electron gun 16 is configured as described above, the uniformity of the beam spot over the entire screen can be improved by the following operation.

That is, if there is no variation in the accuracy of the electrodes and the assembling accuracy and the entire electron gun 16 has a desired astigmatism, the resistance value of the variable resistor 20 disposed outside the tube is set to a predetermined intermediate value. Should be set to. Thereby, desired astigmatism can be obtained in the entire electron gun 16.

On the other hand, if the electron gun 16 has astigmatism in which the focusing action in the vertical direction is stronger than the desired astigmatism of the entire electron gun 16 due to variations in electrode accuracy and assembly accuracy, etc.
The resistance value of the variable resistor 20 is made larger than a predetermined value. Thus, the second electrode element G42 of the fourth grid G4
And the strength of the quadrupole lens formed between the first and second electrode elements G41 and G42 decreases. Since the quadrupole lens has a stronger focusing effect in the vertical direction than in the horizontal direction, the focusing effect in the horizontal direction is stronger than in the vertical direction due to weakening of the strength of the lens. The vertical astigmatism cancels strong astigmatism, and the astigmatism in the entire electron gun 16 can be optimized.

Conversely, if the electron gun 16 has astigmatism whose horizontal focusing action is stronger than the desired astigmatism of the entire electron gun 16 due to variations in electrode precision and assembly precision, etc. The resistance value is made smaller than a predetermined value. As a result, the potential of the second electrode element G42 of the fourth grid G4 decreases, and the strength of the quadrupole lens formed between the first and second electrode elements G41 and G42 increases. Therefore, in this case, the focusing action in the vertical direction is stronger than the horizontal direction, the astigmatism in which the focusing action in the horizontal direction is stronger than the vertical direction is canceled, and the astigmatism in the entire electron gun 16 is optimized. can do.

Therefore, by configuring the electron gun 16 as described above, even if the accuracy of the electrodes and the assembling accuracy fluctuate and the astigmatism changes, the optimum astigmatism can always be obtained. Thus, the uniformity of the beam spot over the entire screen can be optimized, and the optimum focus performance can be obtained. In addition, stable production can be achieved by reducing focus defects.

In the above embodiment, the electron beam passage holes on the sixth grid side of the fifth grid and on the fifth grid side of the sixth grid are vertically elongated holes having a vertical diameter larger than the horizontal diameter. 5, the structure in which astigmatism having a stronger focusing action in the horizontal direction than in the vertical direction is generated between the sixth and sixth grids. This is because the astigmatism which has a stronger focusing action in the horizontal direction than in the vertical direction in the entire electron gun. If the resulting structure
The same effect can be obtained even if another structure is used. For example, a structure in which astigmatism in which the focusing action in the horizontal direction is stronger than the vertical direction in the sub lens is generated.

In the above embodiment, the electron beam passage holes on the second electrode element side of the first electrode element of the fourth grid and the first electrode element side of the second electrode element are horizontally elongated. On the other hand, if the electron beam passage hole of the second electrode element has a structure in which the entire electron gun has astigmatism in which the focusing action in the horizontal direction is stronger than the vertical direction, the vertical diameter is larger than the horizontal diameter. It may be. This is because, with this structure, the fourth grid has astigmatism in which the focusing action in the horizontal direction is stronger than that in the vertical direction, contrary to the conventional electron gun. As long as the desired astigmatism is obtained, the astigmatism of the entire electron gun can be changed by changing the resistance value of the variable resistor disposed outside the tube, and the same effect can be obtained. It is.

Also, contrary to the connection of the electron gun in the above embodiment, the second grid is connected to the second electrode element of the fourth grid, and the first electrode element of the fourth grid is moved closer to the electron gun. Then, it may be connected to one end of a resistor arranged in the tube, connected to the second grid via this resistor, and grounded via a variable resistor at one end of the resistor.

Further, if the fourth grid has a structure in which astigmatism occurs, the fourth grid may be divided into three or more electrode elements. In this case, at least one or more of the divided electrode elements is connected to the second grid, and the other electrode elements are connected to one end of a resistor arranged in a tube close to the electron gun. By connecting to the second grid through the resistor and grounding through the variable resistor, an electron gun having the same effect can be obtained.

In the above embodiment, an in-line type color cathode ray tube has been described. However, the present invention can be applied to a color cathode ray tube having a delta type electron gun. Can be applied to a cathode ray tube that emits light.

[0039]

The present invention has a cathode and first to sixth grids sequentially arranged in the direction of the phosphor screen from the cathode, and a triode section for generating and controlling an electron beam by the cathode and the first to third grids. The sub-lens for pre-focusing the electron beam generated and controlled by the triode by the third to fifth grids, and the electron beam pre-focused by the sub-lens for the fifth and sixth grids are finally focused on the phosphor screen. In a cathode ray tube having an electron gun on which a main lens is formed, a fourth grid is divided into at least two electrode elements, and at least one of these electrode elements is connected to the second grid. Is connected to the second grid via a resistor, and grounded via a variable resistor. The assembling power of the electron gun is different from that of the astigmatism, so that the electron gun as a whole has astigmatism that the focusing power in the horizontal direction is stronger than that in the vertical direction. If the electron lens that has strong astigmatism in the direction and has astigmatism that is strong and the astigmatism of the main lens is formed by the divided electrode elements of the fourth grid, the accuracy of the electrodes and the accuracy of assembly are reduced. Even if the astigmatism changes due to variations, the astigmatism can always be optimized, the beam spot uniformity over the entire screen can be optimized, and optimal focus performance can be obtained. it can. In addition, stable production can be achieved by reducing focus defects.

[Brief description of the drawings]

FIG. 1A is a horizontal sectional view showing a configuration of an electron gun of an in-line type color cathode ray tube according to an embodiment of the present invention, and FIG. 1B is a vertical sectional view.

FIG. 2 is a view showing a shape of an electron beam passage hole of a first electrode element obtained by dividing a fourth grid of the electron gun.

FIG. 3 is a view showing a shape of an electron beam passage hole of a fifth grid of the electron gun.

FIG. 4 is a sectional view showing a configuration of an in-line type color cathode ray tube according to an embodiment of the present invention.

FIG. 5A is a diagram showing a horizontal deflection magnetic field of a self-convergence in-line type color cathode ray tube;
(B) is a diagram showing a vertical deflection magnetic field.

FIG. 6 is a diagram for explaining deflection aberration of a conventional self-convergence in-line type color cathode ray tube.

7A is a horizontal sectional view showing a configuration of a conventional electron gun of an in-line type color cathode ray tube, and FIG. 7B is a vertical sectional view.

[Explanation of symbols]

 12 phosphor screen 15B, 15R ... a pair of side beams 15G ... center beam 16 ... electron gun 17 ... deflecting device 19 ... resistor 20 ... variable resistor 22 ... electron beam passage hole 23 ... electron beam passage hole G1 ... first Grid G2 ... Second grid G3 ... Third grid G4 ... Fourth grid G41 ... First electrode element G42 ... Second electrode element G5 ... Fifth grid G6 ... Sixth grid K ... Cathode

Claims (3)

[Claims] 1. A triode section having a cathode and first to sixth grids sequentially arranged in the direction of the phosphor screen from the cathode, and generating and controlling an electron beam by the cathode and the first to third grids. A sub-lens for pre-focusing the electron beam generated and controlled by the triode by the third to fifth grids, and finally an electron beam pre-focused by the sub-lens by the fifth and sixth grids In a cathode ray tube including an electron gun in which a main lens converging on a phosphor screen is formed, the fourth grid is divided into at least two electrode elements, and at least one of the electrode elements is connected to the first electrode element. The other electrode elements are connected to the second grid via a resistor and connected via a variable resistor. A cathode ray, wherein the electrode element has astigmatism in which the focusing power in the horizontal direction and the focusing power in the vertical direction are different, and the electron gun as a whole has astigmatism in which the focusing power in the horizontal direction is stronger than that in the vertical direction. tube. 2. An electron lens in which a main lens has astigmatism in which a focusing power in a horizontal direction is stronger than a vertical direction, and an astigmatism of the main lens is compensated by divided electrode elements of a fourth grid. The cathode ray tube according to claim 1, wherein 3. An electron lens in which the sub-lens has astigmatism having a stronger focusing power in the horizontal direction than in the vertical direction, and the electrode element divided by the fourth grid forms an electron lens which compensates for the astigmatism of the sub-lens. The cathode ray tube according to claim 1, wherein