JP3734327B2 - Color cathode ray tube equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color cathode ray tube device, and more particularly, to a color cathode ray tube device that displays an excellent image by reducing elliptic distortion of a beam spot at the periphery of a screen.
[0002]
[Prior art]
In general, a color cathode ray tube has an envelope consisting of a panel and a funnel, and deflects three electron beams emitted from an electron gun disposed in the neck of the funnel by horizontal and vertical deflection magnetic fields generated by a deflecting device. The phosphor screen provided on the inner surface of the panel is horizontally and vertically scanned through a shadow mask to display a color image.
[0003]
In such a color cathode ray tube, in particular, the electron gun is an in-line type electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams that pass on the same horizontal plane, and the horizontal deflection magnetic field generated by the deflection device is pinned. A self-convergence in-line type color cathode ray tube that self-concentrates the three electron beams arranged in a row is widely used as a cushion type and a non-uniform magnetic field having a vertical deflection magnetic field as a barrel type.
[0004]
There are various types of electron guns that emit three electron beams arranged in a row, and one of them is an electron gun called a QPF (Quadra Potential Focus) type double focus method. As shown in FIG. 6, the QPF type double focus type electron gun has three cathodes K arranged in a row in the horizontal direction (H-axis direction), and the cathodes K are sequentially arranged in the phosphor screen direction. The first to sixth grids G1 to G6 are provided, and the fifth grid G5 is divided into three grids G51, G52, and G53. These grids G1 to G4, G51 to G53, and G6 are each formed in an integral structure, and three electron beam passage holes are formed in a row in the horizontal direction corresponding to the three cathodes K, respectively.
[0005]
In this electron gun, a voltage of about 150 V is applied to each cathode K, the first grid G1 is grounded, a voltage of about 800 V is applied to the second grid G2, and a voltage of about 6 kV is applied to the third grid G3. The fourth grid G4 is connected to the second grid G2 in the tube and a voltage of about 800V is applied. Of the three grids G51, G52, and G53 of the fifth grid G5, the intermediate grid G52 is connected to the third grid G3, and a voltage of about 6 kV is applied, and the grids G51 and G53 on both sides are connected to each other. Using the voltage applied to the intermediate grid G52 as a reference voltage, a dynamically changing voltage that increases as the electron beam deflects is applied. A high voltage of about 26 kV is applied to the sixth grid G6.
[0006]
By applying such a voltage, in this electron gun, the cathode K and the first and second grids G1, G2 generate an electron beam and form a triode that forms an object point with respect to the main lens described later. A prefocus lens for prefocusing the electron beam from the triode portion by the second and third grids G2 and G3 is further located on the third, fourth grid G3 and fourth grid G4 side. A sub-lens for further prefocusing the electron beam preliminarily focused by the prefocus lens is formed by the grid G51 obtained by dividing the grid G5. A quadrupole lens is formed by the three grids G51, G52, and G53 obtained by dividing the fifth grid G5. Further, a main lens for finally focusing the electron beam on the phosphor screen is formed by the divided grid G53 and the sixth grid G6 of the fifth grid G5 located on the sixth grid G6 side.
[0007]
In this electron gun, when the electron beam is directed toward the center of the phosphor screen without being deflected, a quadrupole lens is not formed between the three divided grids G51, G52, and G53 of the fifth grid G5. The electron beam from the unit is focused on the center of the phosphor screen by the prefocus lens, the sub lens, and the main lens.
[0008]
On the other hand, when the electron beam is deflected toward the periphery of the phosphor screen, the voltages of the grids G51 and G53 on both sides of the fifth grid G5 are increased according to the deflection angle of the electron beam, and divided into three. A quadrupole lens is formed between the grids G51, G52, and G53. At the same time, as the voltage of the grid G53 increases, the strength of the main lens formed by the grid G53 and the sixth grid G6 decreases. As a result, the distance from the electron gun to the phosphor screen is increased electro-optically, the lens magnification changes corresponding to the farther image point, and the horizontal deflection magnetic field generated by the deflection yoke is pincushion type, vertical It compensates for deflection aberration caused by the deflection magnetic field being barrel-shaped.
[0009]
Incidentally, in order to improve the image quality of the color cathode ray tube, it is necessary to improve the focus characteristics of the entire screen. However, in a color cathode ray tube having a normal in-line type electron gun that emits three electron beams arranged in a row, as shown in FIG. 7A, the beam spot 1a at the center of the screen is almost a perfect circle. The beam spot 1b is distorted into an elliptical shape that is long in the horizontal direction (lateral collapse) due to deflection aberration, and a blur 2 is generated in the vertical direction.
[0010]
On the other hand, as described above, the fifth grid G5 is divided into three, and a double focus type electron gun that forms a quadrupole lens that changes in accordance with the deflection of the electron beam between the divided grids G51, G52, and G53. As shown in FIG. 7B, the color cathode ray tube having the above can compensate for the deflection aberration and can eliminate the blur of the beam spot 1b in the peripheral portion of the screen, thereby focusing the electron beam over the entire screen. it can. However, even with this double focus type electron gun, the horizontal collapse of the beam spot 1b at the periphery of the screen cannot be resolved, and moire is caused by interference with the electron beam passage hole of the shadow mask, and characters on the screen are displayed. There is a problem that it becomes difficult to see.
[0011]
As a countermeasure, there is an electron gun in which a horizontally long groove is formed on the surface of the second grid facing the third grid. When a horizontally long groove is formed in the second grid in this way, the vertical focusing action of the prefocus lens formed by the second and third grids is stronger than the horizontal focusing action, and in the horizontal direction with respect to the main lens. The virtual object point diameter can be reduced and the virtual object point diameter in the vertical direction can be increased. As a result, as shown in FIG. 7 (c), the beam spot 1a at the center of the screen is made to be vertically long, and at the same time, the lateral collapse of the beam spot 1b at the peripheral part is alleviated to interfere with the electron beam passage hole of the shadow mask. Moire caused by the above can be eliminated.
[0012]
In this electron gun, as the horizontal groove of the second grid is deepened, the lateral collapse of the beam spot 1b in the peripheral portion of the screen can be reduced, but along with this, the vertical beam spot 1a is promoted in the central portion of the screen. The resolution at the center of the screen deteriorates due to the enlargement of the vertical diameter of the beam spot.
[0013]
[Problems to be solved by the invention]
As described above, in order to improve the image quality of the color cathode ray tube, it is necessary to maintain a good focus state over the entire screen and reduce the elliptic distortion of the beam spot.
[0014]
In this regard, the conventional QPF type double focus type electron gun applies a voltage that increases in accordance with the deflection of the electron beam to the grid forming the quadrupole lens, thereby blurring the beam spot in the vertical direction due to deflection aberration. It can be solved. However, the horizontal collapse of the beam spot at the periphery of the screen cannot be eliminated, and moire is caused by interference with the electron beam passage hole of the shadow mask, making it difficult to see the display of characters on the screen.
[0015]
In order to eliminate the horizontal collapse of the beam spot at the peripheral portion of the screen, if the horizontally elongated groove is formed on the surface of the second grid facing the third grid, the horizontal collapse of the beam spot at the peripheral portion of the screen can be eliminated. However, the beam spot at the center of the screen becomes vertically long, and the resolution at the center of the screen deteriorates.
[0016]
Therefore, in the above conventional electron gun, if emphasis is placed on the visibility of the image in the center portion of the screen, the image in the peripheral portion of the screen will be deteriorated. The image at the center is deteriorated. For this reason, the conventional color cathode ray tube has a problem that the entire screen cannot be brought into a favorable focus state and must be designed in a compromise manner.
[0017]
The present invention has been made to solve the above-described problems, and has an object to improve the focus characteristics over the entire screen and reduce the elliptic distortion of the beam spot.
[0020]
[Means for Solving the Problems]
( 1 ) A cathode, first and second grids that are sequentially adjacent to the cathode and spaced apart by a predetermined distance to control the electron beam from the cathode, and the electron beam controlled by the first and second grids is accelerated and focused. An electron gun having a third grid and at least three grids, and a pincushion type horizontal deflection magnetic field for deflecting an electron beam emitted from the electron gun in the horizontal direction and a barrel type vertical deflection magnetic field for deflecting in the vertical direction are generated. In a color cathode ray tube apparatus including a deflection yoke, an auxiliary second grid to which a dynamically changing voltage is applied between the second grid and the third grid in synchronization with a magnetic field generated by the deflection yoke is applied to the electron gun. Placed, and these 2nd grid, auxiliary 2nd grid and 3rd grid have stronger vertical focusing than horizontal focusing An electron lens having astigmatism and dynamically changing the intensity of astigmatism is formed by a dynamically changing voltage applied to the auxiliary second grid, and the third and subsequent grids are formed along the electron beam traveling direction. With the three grids arranged, the horizontal focusing has a stronger astigmatism than the vertical focusing and is caused by the dynamically changing voltage applied to the grids located on both sides of the three grids. An electron lens that dynamically changes the intensity of astigmatism is formed.
[0021]
( 2 ) In the color cathode-ray tube of ( 1 ), a voltage that decreases in synchronization with the magnetic field generated by the deflection yoke is applied to the auxiliary second grid using the voltage applied to the second grid as a reference voltage. Among them, a voltage that increases in synchronization with the magnetic field generated by the deflection yoke is applied to the grids positioned on both sides using the voltage applied to the grid positioned in the middle as a reference voltage.
[0022]
( 3 ) In the color cathode ray tube apparatus of (1) or (2), a non-circular electron beam passage hole having a horizontal diameter larger than a vertical diameter is formed in the auxiliary second grid.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0024]
FIG. 3 shows a configuration of an inline type color cathode ray tube device as one form thereof. This color cathode-ray tube apparatus has an envelope made up of a substantially rectangular panel 10 and a funnel-shaped funnel 11, and dot-shaped three-color fluorescence that emits blue, green, and red light on the inner surface of the panel 10. A phosphor screen 12 made of a body layer is provided, and a shadow mask 13 is disposed inside the phosphor screen 12 so as to face the phosphor screen 12. On the other hand, in the neck 15 of the funnel 11, the following electron gun 17 is disposed that emits a three-beam arrangement of three electron beams 16B, 16G, and 16R composed of a center beam 16G and a pair of side beams 16B and 16R passing through the same horizontal plane. ing. A deflection yoke 20 for generating a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field is mounted outside the vicinity of the boundary between the large diameter portion 18 and the neck 15 of the funnel 11. Then, the three electron beams 16B, 16G, and 16R emitted from the electron gun 17 are deflected by horizontal and vertical magnetic fields generated by the deflecting device 20 mounted outside the funnel 11, so that the phosphor screen 12 is horizontal and vertical. By scanning, a structure for displaying a color image is formed.
[0025]
The electron gun 17 is a QPF type double focus system, and as shown in FIG. 1, three cathodes K arranged in a line in the horizontal direction (H-axis direction), and three each for heating the cathodes K separately. Heaters (not shown), and first to sixth grids G1 to G6 arranged sequentially from the cathode K in the phosphor screen direction at a predetermined interval. The fifth grid G5 is divided into three grids G51, G52, and G53 that are sequentially arranged from the fourth grid G4 to the sixth grid G6. Further, in the electron gun 17, an auxiliary second grid G2s is disposed between the second grid G2 and the third grid G3.
[0026]
Among the divided grids G51, G52, and G53 of the first and second grids G1 and G2, the auxiliary second grid G2s, the third, fourth grids G3 and G4, and the fifth grid G5, the grid G52 located in the middle. Are each composed of an integrally structured plate-like electrode having a major axis in the arrangement direction of the cathodes K. Of the divided grids G51, G52, and G53 of the fifth grid G5, the grids G51 and G53 located on both sides are each formed of an integrally structured cylindrical electrode having a major axis in the arrangement direction of the cathode K. The sixth grid G6 is composed of cup-shaped electrodes.
[0027]
The first, second, third, and fourth grids G1, G2, G3, and G4 made of the plate-like electrodes have three circular electron beam passage holes in the horizontal direction corresponding to the three cathodes K, respectively. Are arranged in a row . Similarly, three circular electron beam passes corresponding to the three cathodes K on the opposing surfaces of the grids G51 and G53 made of cylindrical electrodes and the adjacent grid of the sixth grid G6 made of cup-shaped electrodes. The holes are formed in a row in the horizontal direction. On the other hand, in the auxiliary second grid G2s, as shown in FIG. 2, corresponding to the three cathodes K, the noncircular electron beam passage holes 22B, 22G, 22R is formed in a row in the horizontal direction.
[0028]
In this electron gun 17, a voltage of about 150V is applied to each cathode K, the first grid G1 is grounded, and a voltage of about 800V is applied to the second grid G2. In the auxiliary second grid G2s, a voltage (about 800V) applied to the second grid G2 is used as a reference voltage, and the voltage dynamically changes in synchronization with the magnetic field generated by the deflection yoke, that is, FIG. And as shown in (b), with the voltage 24 applied to the second grid as a reference voltage, voltages 26H and 26V that decrease in a parabolic manner are applied in synchronization with the horizontal deflection current 25H and the vertical deflection current 25V. . A voltage of about 6 kV is applied to the third grid G3. The fourth grid G4 is connected to the second grid G2 in the tube, and a voltage of about 800V is applied. Among the divided grids G51, G52, G53 of the fifth grid G5, the grid G52 located in the middle is connected to the third grid G3 in the tube, and a voltage of about 6 kV is applied. On the other hand, the grids G51 and G53 located on both sides are connected in the pipe, and the magnetic fields generated by the deflection yoke are applied to the grids G51 and G53 with the voltage (about 6 kV) applied to the grid G52 as a reference voltage. In other words, a voltage that changes dynamically in synchronization with each other, that is, a voltage that increases in a parabolic manner is applied in synchronization with the horizontal deflection current and the vertical deflection current. A high voltage of about 26 kV is applied to the sixth grid G6.
[0029]
By applying the voltage, the electron gun 17 forms a triode that generates an electron beam by the cathode K and the first and second grids G1 and G2 and forms an object point with respect to a main lens described later. A prefocus lens for prefocusing the electron beam from the triode by the second grid G2, auxiliary second grid G2s and third grid G3 is further provided on the third, fourth grid G3, G4 and fourth grid G4 sides. A sub-lens for further prefocusing the electron beam preliminarily focused by the prefocus lens is formed by the grid G51 obtained by dividing the fifth grid G5. A quadrupole lens that compensates for deflection aberration is formed by the three grids G51, G52, and G53 obtained by dividing the fifth grid G5. Further, a main lens for finally focusing the electron beam on the phosphor screen is formed by the divided grid G53 and the sixth grid G6 of the fifth grid G5 located on the sixth grid G6 side.
[0030]
In this electron gun 17, when the electron beam is directed toward the center of the phosphor screen without being deflected (when it is not deflected), the electron beam from the triode is transmitted to the second grid G 2, the auxiliary second grid G 2 s and the second one. Pre-focusing is performed by a prefocus lens formed by three grids G3. In this case, since the auxiliary second grid G2s has a noncircular electron beam passage hole having a horizontal diameter larger than the vertical diameter, Due to weak negative astigmatism (astigmatism in which vertical focusing is stronger than horizontal focusing), the horizontal virtual object point diameter with respect to the main lens is reduced, and the horizontal divergence angle is increased. Next, the electron beam prefocused by the prefocus lens is further prefocused by a sub lens formed by a grid G51 divided from the third, fourth grid G3, G4 and the fifth grid G5. In this case, no electron lens is formed between the three divided grids G51, G52, and G53 of the next fifth grid G5. Therefore, the electron beam prefocused by the sub-lens is applied to the grids G51, G52. , G53, and finally converged by the main lens formed by the divided grid G53 and the sixth grid G6 of the fifth grid G5, and enters the center of the phosphor screen.
[0031]
As a result, as shown in FIG. 5, the beam spot 28a of the electron beam incident on the center of the phosphor screen becomes a slightly vertically long circle due to the weak negative astigmatism caused by the auxiliary second grid G2s.
[0032]
On the other hand, when the electron beam is deflected in the peripheral direction of the phosphor screen (during the deflection), the electron beam from the triode is caused by the second grid G2, the auxiliary second grid G2s, and the third grid G3. Pre-focusing is performed by the formed prefocus lens. In this case, however, the voltage of the auxiliary second grid G2s becomes lower as the deflection angle increases (see FIG. 4) than in the case of no deflection (see FIG. 4). As a result of this astigmatism, the virtual object point diameter in the horizontal direction relative to the main lens is smaller and the virtual object point diameter in the vertical direction is larger than in the case of no deflection. Also, the divergence angle in the horizontal direction is increased and the divergence angle in the vertical direction is reduced as compared with the case of no deflection. Next, the electron beam prefocused by the prefocus lens is further prefocused by a sub lens formed by a grid G51 divided from the third, fourth grid G3, G4 and the fifth grid G5. Next, at the time of this deflection, since the voltage applied to the grid G52 as a reference voltage is applied to the divided grids G51 and G53 of the fifth grid G5, the voltage that increases as the deflection angle increases is applied. G52 and G53 receive positive astigmatism (horizontal focusing is stronger than vertical focusing), the divergence angle by the prefocus lens is corrected, and the deflection aberration is corrected. . Thereafter, the light is finally focused by the main lens formed by the divided grid G53 and the sixth grid G6 of the fifth grid G5, and enters the peripheral portion of the phosphor screen.
[0033]
The beam spot of the electron beam incident on the peripheral portion of the phosphor screen is reduced in the horizontal diameter because the virtual object spot diameter in the horizontal direction is reduced due to strong negative astigmatism caused by the auxiliary second grid G2s. On the other hand, the vertical diameter is increased by increasing the virtual object point diameter in the vertical direction. As a result, as shown in FIG. 5, the beam spot 28b of the electron beam incident on the peripheral portion of the phosphor screen is relaxed and becomes almost circular.
[0034]
Therefore, when the electron gun 17 is configured as described above, the elliptical distortion of the beam spot can be alleviated over the entire surface of the screen to make it substantially circular, and the focus state on the entire screen can be made uniform to display a good image. A cathode ray tube device can be constructed.
[0035]
【The invention's effect】
As described above, the cathode, the first and second grids, which are sequentially adjacent to the cathode and spaced apart by a predetermined distance and control the electron beam from the cathode, accelerate the electron beam controlled by the first and second grids, An electron gun having a third grid for focusing and at least one grid, a pincushion type horizontal deflection magnetic field for deflecting an electron beam emitted from the electron gun in the horizontal direction, and a barrel type vertical deflection magnetic field for deflecting in the vertical direction In a color cathode ray tube apparatus including a deflection yoke that generates the auxiliary second grid to which a voltage that dynamically changes in synchronization with the magnetic field generated by the deflection yoke is disposed between the second grid and the third grid. The astigmatism that the vertical focusing is stronger than the horizontal focusing due to the second grid, the auxiliary second grid, and the third grid. A structure that forms an electron lens that has a difference and dynamically changes the intensity of astigmatism by a dynamically changing voltage applied to the auxiliary second grid, and dynamically changes the virtual object point diameter of the electron beam. Therefore, it is possible to reduce the horizontal collapse of the beam spot at the periphery of the screen, make the focus state of the entire screen uniform, and configure a color CRT device that displays a good image.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an electron gun of an inline type color cathode ray tube according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of an auxiliary second grid of the electron gun.
FIG. 3 is a diagram showing a configuration of an inline type color cathode ray tube according to an embodiment of the present invention.
FIGS. 4A and 4B are diagrams showing voltages that change in synchronization with a deflection current applied to the auxiliary second grid, respectively.
FIG. 5 is a view for explaining the shape of a beam spot on a phosphor screen of an inline type color cathode ray tube according to an embodiment of the present invention.
FIG. 6 is a diagram showing a configuration of a conventional electron gun of an inline type color cathode ray tube.
7A is a diagram for explaining the shape of a beam spot on a phosphor screen of a color cathode ray tube having a conventional normal in-line electron gun, and FIG. 7B is a conventional QPF double FIG. 7C is a diagram for explaining the shape of a beam spot on a phosphor screen of a color cathode ray tube having a focus type electron gun. FIG. 7C shows a horizontally long groove formed in the second grid of the QPF type double focus type electron gun. It is a figure for demonstrating the shape of the beam spot on the fluorescent substance screen of the color cathode ray tube which has an electron gun.
[Explanation of symbols]
12 ... Phosphor screens 16B, 16R ... Pair of side beams 16G ... Center beam 17 ... Electron gun 20 ... Deflection yoke G1 ... First grid G2 ... Second grid G2s ... Auxiliary second grid G3 ... Third grid G4 ... Fourth Grid G5 ... Fifth grid G51 ... Divided grid G52 of fifth grid ... Divided grid G53 of fifth grid ... Divided grid G6 of fifth grid ... Sixth grid K ... Cathode

Claims (3)

A cathode, first and second grids that are sequentially adjacent to the cathode and spaced apart from each other by a predetermined distance to control the electron beam from the cathode, and the electron beam controlled by the first and second grids is accelerated and focused. 3 an electron gun having a grid and at least three grids, deflection for generating differentially barrel type vertical deflection magnetic field for deflecting the pincushion horizontal deflection magnetic field and the vertical deflecting the electron beams in the horizontal direction emitted from the electron gun In a color cathode ray tube device comprising a yoke,
In the electron gun, an auxiliary second grid to which a voltage that dynamically changes in synchronization with a magnetic field generated by the deflection yoke is applied is disposed between the second grid and the third grid. The auxiliary second grid and the third grid have astigmatism in which the vertical focusing is stronger than the horizontal focusing, and the intensity of the astigmatism is increased by the dynamically changing voltage applied to the auxiliary second grid. form forms a dynamically changing electron lens, quadrupole lens formed by the three grids being disposed in the third and subsequent grid along the electron beam traveling direction from the focussing focusing in the horizontal direction in the vertical direction to form an electron lens intensity of the astigmatic aberration is dynamically changed by dynamically changing voltage is also applied to a strong astigmatism have and located on either side of these three grid grid Color cathode ray tube apparatus characterized by. A voltage that decreases in synchronization with the magnetic field generated by the deflection yoke is applied to the auxiliary second grid using the voltage applied to the second grid as a reference voltage , and the grid located on both sides of the three grids is applied to the auxiliary grid. 2. The color cathode ray tube device according to claim 1, wherein a voltage that increases in synchronization with a magnetic field generated by the deflection yoke is applied with reference to a voltage applied to a grid located in the middle . 3. The color cathode ray tube apparatus according to claim 1, wherein a non-circular electron beam passage hole having a horizontal diameter larger than a vertical diameter is formed in the auxiliary second grid.

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