JPH052997A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To improve resolution on the whole area of a phosphor screen. CONSTITUTION:In a cathode-ray tube deflecting electron beams emitted from an electron gun composed of 1st to 6th grids arranged in order on a cathode K, by pin cushion type horizontal deflection magnetic field and barrel type vertical deflection field, dynamic voltage which changes in synchronization with deflection is applied to 3rd and 5th grids, G3 an G5, and a 4th grid G4 is composed of 1st to 3rd electron elements G41 to G43 placed in order in the direction from the 3rd grid G3 to the 5th grid G5. The 1st and the 3rd electron element G41 to G43 are formed in the shape of a cylindrical part and an elliptical cylinder part 23 which are formed at one end of each element G41, G43 and have a longer diameter in the horizontal direction where they face each other. On the 2nd electron element G42, a round electron beam passing aperture 24 and a pair of electron boards 25 are formed. The boards 25 are arranged to protrude into the elliptical cylinder part 23 of the 1st and 3rd electron elements, while holding G41 to G43 the electron beam passing hole 24 therebetween in the horizontal direction. The electron elements G41 to G43 are thereby formed, to which dynamic voltage changing in accordance with the deflection is applied.

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, and more particularly to a cathode ray tube which is suitable for a monochrome cathode ray tube used for a display device for a terminal and which can obtain a high resolution over the entire phosphor screen.

[0002]

2. Description of the Related Art Generally, a cathode ray tube for displaying an image has a phosphor screen, an electron gun, and the like arranged in an envelope, and an electron beam emitted from the electron gun is attached to the outside of the envelope. Is formed by horizontally and vertically scanning the phosphor screen by deflecting by the horizontal and vertical deflection magnetic fields generated by the above.

Among such cathode ray tubes, especially for terminal display devices, the electron gun is a quadrapotential type which can obtain a high resolution, and a pincushion type horizontal type is used to correct the figure distortion when the electron gun is deflected. There is a monochrome cathode ray tube that combines a deflection yoke that generates an inhomogeneous magnetic field composed of a deflection magnetic field and a barrel-shaped vertical deflection magnetic field.

FIG. 8 shows a quadrapotential type electron gun of this monochrome cathode ray tube. This quadra-potential type electron gun has a cathode K and first to sixth grids G1 to G6 sequentially arranged on the cathode K, and these are integrally fixed by a pair of insulating supports 1. Has been formed. In this electron gun, the third to sixth grids G3 to G6 are composed of cylindrical electrodes, and these electrodes form a main lens unit for finally focusing the electron beam.

However, even if the quadra-potential type electron gun which can obtain the above-mentioned high resolution is used, when it is combined with a deflection yoke which generates a non-uniform magnetic field, the electron beam becomes
The horizontal deflection magnetic field generated by the deflection yoke causes a diverging action in the horizontal direction and a converging action in the vertical direction to distort the cross-sectional shape into an elliptical shape having a major axis in the horizontal direction. Further, the vertical deflection magnetic field is subjected to a focusing action in the horizontal direction and a diverging action in the vertical direction, thereby causing a deflection aberration that is distorted into an elliptical shape having a major axis in the vertical direction. With respect to the diagonal deflection of the phosphor screen, the actions of the horizontal deflection magnetic field and the vertical deflection magnetic field are contradictory, so that the distortion of the cross-sectional shape of the electron beam is reduced.

Furthermore, since the trajectory of the electron beam emitted from the electron gun becomes long as the deflection of the electron beam increases, even if the optimum focus voltage is set at the center of the phosphor screen, In the periphery of the screen,
The camera is overfocused.

As a result, as shown in FIG. 9, even if the beam spot 3a in the central portion of the phosphor screen 2 is a perfect circle, the beam spots 3b in the peripheral portion have a high-brightness core portion 4 and a low-brightness halo. A non-circular shape composed of the portion 5 and the resolution is significantly deteriorated in the peripheral portion of the phosphor screen 1.

As means for correcting the distortion of the beam spot in the peripheral portion of the phosphor screen as described above, Japanese Patent Laid-Open No. 61-
74246, JP-A-63-143725,
JP-A-63-241842, JP-A-64-7103
No. 9, gazette discloses an in-line type color picture tube having an electron gun which emits three electron beams arranged in a line passing through the same plane, and among the plurality of electrodes constituting the main lens portion of the electron gun, a unipotential The low-voltage side electrode forming the lens is divided into three electrode elements, a non-circular electron beam passage hole is provided in each of these electrode elements to form an asymmetric lens, and the deflection yoke is deflected to any one of the electrode elements. It is shown that the deflection aberration is corrected by applying a dynamic voltage that changes in synchronization with.

However, when this technique is applied to the electron gun for a monochrome cathode ray tube described above, in the electron gun shown in FIG. 8, the third to sixth grids forming the main lens portion have a cylindrical shape. Such problems arise.

That is, the electrodes forming the main lens portion of the electron gun shown in FIG.
As shown in Japanese Patent Publication, it is divided into three electrode elements,
If a non-circular electron beam passage hole is formed in the electrode element, the divided electrode element also has a cylindrical shape, so that the minor diameter of the non-circular electron beam passage hole is necessarily smaller than the inner diameter of the electrode element.

By the way, generally, the performance of the electron lens becomes better as the hole diameter of the electrode constituting the lens becomes larger, and the beam spot diameter obtained on the phosphor screen becomes smaller due to the focusing of the electron lens. Therefore, in the structure where the minor diameter is smaller than the inner diameter of the electrode element due to the non-circular electron beam passage hole as described above, the lens performance of the main lens portion is deteriorated, and the beam spot diameter on the phosphor screen is increased, The resolution deteriorates.

On the other hand, in such a cylindrical electrode element, in order to increase the minor diameter of the non-circular electron beam passage hole, it is necessary to increase the outer diameter of the electrode element. As a result, the neck diameter of the outer envelope becomes large, which causes an increase in deflection power.

[0013]

As described above, a monochrome in which a quadrapotential type electron gun which can obtain high resolution and a deflection yoke which generates an inhomogeneous magnetic field in order to correct the graphic distortion during deflection are combined. The cathode ray tube has a problem that the beam spot is distorted in the peripheral portion of the phosphor screen due to the nonuniformity of the magnetic field generated by the deflection yoke, and the resolution is significantly deteriorated.

In order to correct the distortion of the beam spot in the peripheral portion of the phosphor screen, the electrodes forming the main lens portion are composed of three electrode elements as is known in the electron gun of the in-line type color picture tube. If a non-circular electron beam passage hole is formed in the electrode element by dividing the electrode element, since the electrode forming the main lens part of the electron gun for a monochrome cathode ray tube has a cylindrical shape, the short diameter of the non-circular electron beam passage hole is small. As a result, the lens performance of the main lens unit deteriorates and the resolution deteriorates. On the other hand, if the outer diameter of the electrode element is increased in order to increase the short diameter of the non-circular electron beam passage hole in this cylindrical electrode element, the neck diameter of the envelope containing the electron gun increases, and the deflection power is increased. There is a problem that leads to the increase of.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a cathode ray tube, particularly a monochrome cathode ray tube, with high resolution over the entire phosphor screen.

[0016]

An electron gun having a cathode and first to sixth grids arranged in this order from the cathode in the phosphor screen direction is provided, and an electron beam emitted from the electron gun is deflected by a deflection yoke. In a cathode ray tube that displays an image on a phosphor screen by being deflected by an inhomogeneous magnetic field composed of a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field, the third and fifth grids of the electron gun are deflected. An electrode to which a dynamic voltage that changes in synchronization with the deflection of the yoke is applied is used, and the fourth grid located between these third and fifth grids is the third grid.
It is composed of first, second and third electrode elements which are sequentially positioned from the grid in the fifth grid direction, and the first of these electrode elements
The electrode element and the third electrode element have a shape including a cylindrical portion and a long cylindrical portion formed at one end of the cylindrical portion and having a major axis in the horizontal direction facing each other, and a circular electron beam passage hole for the second electrode element. And a pair of electrode plates projecting into the elongated cylindrical portions of the first and third electrode elements sandwiching the electron beam passage hole from the horizontal direction, and a dynamic voltage that changes in synchronization with the deflection of the deflection yoke is applied. Electrode element.

[0017]

When the electron gun is constructed as described above, when the electron beam is not deflected, the dynamic voltage applied to the second electrode element is made the same as the voltage applied to the first and third electrode elements, A rotationally symmetric lens can be formed between the second and third electrode elements.

In the horizontal scanning period in which the electron beam is deflected in the horizontal direction, the dynamic voltage applied to the second electrode element is set lower than the voltage applied to the first and third electrode elements, so that It is possible to form a non-rotationally symmetric lens that exerts a converging action on the electron beam in the horizontal direction and a diverging action in the vertical direction between the second and third electrode elements, and a pin cushion type horizontal deflection magnetic field of the deflection yoke is formed. It is possible to form an elliptical shape having a long axis in the vertical direction that cancels the deflection aberration based on the vertical axis.

In the vertical scanning period in which the electron beam is deflected in the vertical direction, the dynamic voltage applied to the second electrode element is set higher than the voltage applied to the first and third electrode elements, and It is possible to form a non-rotationally symmetric lens that exerts a diverging action in the horizontal direction and a focusing action in the vertical direction on the electron beam between the second and third electrode elements, and is based on the barrel-shaped vertical deflection magnetic field of the deflection yoke. An elliptical shape having a major axis in the horizontal direction that cancels the deflection aberration can be used.

Therefore, due to the action of the non-rotationally symmetric lens formed between the first, second and third electrode elements, it is possible to prevent the deterioration of the resolution in the peripheral portion of the phosphor screen.

[0021]

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

FIG. 7 shows the overall construction of a monochrome cathode ray tube which is one of the embodiments. This cathode ray tube has an envelope including a face plate 10 and a funnel-shaped funnel 11 integrally welded to the face plate 10, and a phosphor screen 12 is formed on the inner surface of the face plate 10, and the funnel 11 is formed. Single electron beam 14 inside neck 13
An electron gun 15 that emits is emitted. Then, the electron beam 14 emitted from the electron gun 15 is applied to a pincushion-type horizontal deflection magnetic field and a barrel-type vertical deflection magnetic field generated by a deflection yoke 17 mounted outside the boundary between the large-diameter portion 16 of the funnel 11 and the neck 13. The structure is such that an image is displayed on the phosphor screen 12 by deflecting it by a magnetic field and scanning the phosphor screen 12 horizontally and vertically.

The electron gun 15 is a quadrapotential type electron gun, and as shown in FIG. 1, one cathode K and first to sixth grids sequentially arranged from the cathode K in the phosphor screen direction. G1 to G6 are formed, and the cathode K and the first to sixth grids G1 to G6 are integrally fixed by a pair of insulating supports 20 via a support 19.

The first and second grids G1 and G2 are composed of disc-shaped electrodes, and are arranged from the third, fifth and sixth grids G3 and G.
5 and G6 are cylindrical electrodes, and electron beam passage holes are formed in these electrodes respectively corresponding to the cathodes K. In addition, the fourth grid G4, as shown in FIG.
It is divided into first, second, and third electrode elements G41, G42, and G43 which are sequentially arranged from the third grid side in the fifth grid direction.

The first and third electrode elements G41, G43
Is attached to one end of the cylindrical portion 22 in the horizontal direction (X
A major axis (axial direction) is taken as a major axis, and a width in the vertical direction is equal to the inner diameter of the major cylindrical section (22). On the other hand, as shown in FIG. 4, the second electrode element G42 is composed of a plate-shaped electrode having an electron beam passage hole 24 corresponding to the cathode K, and the electron beam passage holes 24 are formed on both sides of the plate surface. A pair of electrode plates 25 are provided on both sides in the horizontal direction so as to sandwich them.
These first, second and third electrode elements G41, G42, G43
As shown in FIG. 2, the long cylindrical portions 23 of the first electrode element G41 and the third electrode element G43 are opposed to each other, and the electrodes of the second electrode element G42 are placed inside the facing long cylindrical portions 23. It is arranged so that the plate 25 is located.

The following voltages are applied to the electrodes of the electron gun 15 during operation. That is, the cathode K has 50 to 1
A voltage obtained by superimposing a video signal on a voltage of 50V is applied, the first grid G1 is grounded (0V), and the first and third electrode elements G41 and G43 of the second grid G2 and the fourth grid G4 are connected. The voltage Vc2 of 600 to 1000 V is the fourth
As shown in FIG. 5, the second electrode element G42 of the grid G4 receives a voltage (Vc2 + Vd1) obtained by superimposing a dynamic voltage Vd1 which changes in synchronization with the deflection current flowing in the deflection yoke on the basis of Vc2 as a reference voltage. The third grid G3 and the fifth grid G5 are connected to each other, and as shown in FIG. 6, a predetermined reference voltage (focus voltage) Vf on which a dynamic voltage Vd2 that changes in synchronization with the deflection current flowing through the deflection yoke is superimposed. (Vf + Vd2), and 1 for the sixth grid G6
A voltage (anode voltage) Va of 5 to 20 kV is applied.

As shown in FIG. 5, the fourth grid G4 is used.
Voltage (Vc2 + Vd1) applied to the second electrode element G42 of
Is a dynamic voltage Vd1 that changes in synchronization with the deflection current.
Changes across a constant reference voltage Vc2, and the horizontal deflection voltage V
Of the envelopes 27a and 27b of H, the envelope 27a at the upper end coincides with the reference voltage Vc2 at the center of one vertical scanning period 28, and the envelope 27b at the lower end coincides with the reference voltage Vc2 at both ends of the one vertical scanning period 28. Has been adjusted to In addition, FIG.
As shown in FIG. 5, the voltage (Vf + Vd2) applied to the third grid G3 and the fifth grid G5 is always higher than the predetermined reference voltage Vf, and is the dynamic voltage Vd2 that changes in synchronization with the deflection current. Envelopes 29a and 29b of the horizontal deflection voltage VH
Among them, the envelope 28b at the lower end is adjusted so as to coincide with the reference voltage Vf in the center of one vertical scanning period 28.

By applying the above voltage, a unipotential type sub-lens is formed between the third to fifth grids G3 to G5 in the electron gun 15, and the fifth and sixth grids G5 and G6 are formed.
A bipotential type main lens is formed therebetween, and these electron lenses focus the electron beam emitted from the cathode K onto the phosphor screen.

In this case, the second electrode element of the fourth grid G4
When the electron beam is not deflected (the deflection amount is 0), the dynamic voltage Vd1 that changes in synchronization with the deflection current applied to G42 is as shown in FIG.
It has the same value as the voltage Vc2 applied to the electrode elements G41 and G43. Therefore, no non-rotationally symmetric lens is formed between the first to third electrode elements G41 to G43, and the sub-lens formed between the third to fifth grids G3 to G5 is a rotation symmetric lens. On the other hand, at this time, the third and fifth grids
A focus voltage Vf that minimizes the beam spot on the phosphor screen is applied to G3 and G5.

Further, when the electron beam is deflected in the horizontal direction, that is, in the horizontal scanning period 30, the dynamic voltage Vd1 that changes in synchronization with the deflection current applied to the second electrode element G42 of the fourth grid G4 is 1st and 3rd electrode element G4
1, which is lower than the voltage Vc2 applied to G43. Therefore, between the first to third electrode elements G41 to G43, as shown in FIG.
As shown by arrows 31 and 32 in (a), a non-rotational symmetry that exerts a focusing action in the horizontal direction (X-axis direction) and a diverging action in the vertical direction (Y-axis direction) on the electron beam 14. A lens is formed. As a result, the first to third electrode elements G41
The electron beam 14 passing between G43 and G43 has an elliptical shape with a major axis in the vertical direction, and cancels the elliptical shape with the major axis in the horizontal direction generated by the pincushion-type horizontal deflection magnetic field of the deflection yoke.

When the electron beam is deflected in the vertical direction, that is, in the vertical scanning period 28, the dynamic voltage Vd1 that changes in synchronization with the deflection current applied to the second electrode element G42 of the fourth grid G4 is 1st and 3rd electrode element G4
1, which is higher than the voltage Vc2 applied to G43. Therefore, between the first to third electrode elements G41 to G43, as shown in FIG.
As indicated by arrows 33 and 34 in (b), a non-rotationally symmetric lens that forms a diverging action in the horizontal direction and a focusing action in the vertical direction with respect to the electron beam 14 is formed. As a result, the electron beam 14 passing between the first to third electrode elements G41 to G43 has an elliptical shape having a major axis in the horizontal direction, and an ellipse having a major axis in the vertical direction generated by the barrel-shaped vertical deflection magnetic field of the deflection yoke. It cancels the deflection aberration that makes the shape.

When the electron beam is deflected in the diagonal direction, the horizontal and vertical deflection aberrations are canceled out, and the correction by the non-rotationally symmetric lens is unnecessary. On the other hand, the second electrode of the fourth grid G4 is used. The dynamic voltage Vd1 that changes in synchronization with the deflection current applied to the element G42 has the same value as the voltage Vc2 applied to the first and third electrode elements G41 and G43, and a non-rotationally symmetric lens is not formed. Therefore, no correction is made.

On the other hand, the dynamic voltage Vd2 that changes in synchronization with the deflection current applied to the third grid G3 and the fifth grid G5 is as shown in FIG.
In both cases of vertical deflection and diagonal deflection, the voltage becomes higher than the optimum focus voltage Vf at the central portion of the phosphor screen, weakening the focusing action of the entire main lens portion. Therefore, the overfocus state, which occurs because the trajectory of the electron beam emitted from the electron gun becomes longer as the deflection increases, is corrected.

Therefore, by using the electron gun 15 constructed as described above, the deflection aberration in the peripheral portion of the phosphor screen 12 and the overfocus state due to the lengthening of the orbit of the electron beam are solved, and the center of the phosphor screen 12 is solved. The resolution of the peripheral portion can be significantly improved without deteriorating the resolution of the portion.

Moreover, in this electron gun 15, the fourth grid
G4 is divided into three, and the first and third electrode elements G41, G43
At the end of each of the
Since a long cylindrical portion 23 having a width equal to the inner diameter of the second cylindrical electrode 23 is formed and the electrode plate 25 of the second electrode element G42 is located inside each long cylindrical portion 23, a small diameter portion which deteriorates the lens performance. , And each of the three divided electrode elements G41, G42,
Since the pair of insulating supports 20 for integrally fixing G43 together with the other electrodes are arranged in the width direction of each long cylindrical portion 23, it is not necessary to increase the distance between the pair of insulating supports 20 and the conventional cathode ray tube. You can place the electron gun 15 in the neck of the same diameter as the neck of
An increase in deflection power can be avoided.

[0036]

The pincushion-type horizontal deflection magnetic field and the barrel-type vertical deflection magnetic field generated by the deflection yoke of the electron beam emitted from the electron gun in which the first to sixth grids are sequentially arranged from the cathode in the phosphor screen direction. In a cathode ray tube that is deflected by a non-uniform magnetic field to display an image on a phosphor screen, a dynamic voltage that changes in synchronization with the deflection of the deflection yoke is applied to the third grid and the fifth grid of the electron gun. Electrode and the fourth grid located between these third and fifth grids is the third grid.
It is composed of first, second and third electrode elements which are sequentially positioned from the grid in the fifth grid direction, and the first of these electrode elements
The electrode element and the third electrode element have a shape including a cylindrical portion and a long cylindrical portion formed at one end of the cylindrical portion and having a major axis in the horizontal direction facing each other, and a circular electron beam passage hole in the second electrode element. A pair of electrode plates projecting into the elongated cylindrical portions of the first and third electrode elements are formed so as to sandwich the electron beam passage hole from the horizontal direction, and a dynamic voltage that changes in synchronization with the deflection of the deflection yoke is applied. When the electrode element is used, it is possible to construct a cathode ray tube having a good resolution over the entire phosphor screen without avoiding an increase in neck diameter that increases deflection power and without deteriorating the performance of the main lens portion.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an electron gun of a monochrome cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a fourth grid of the electron gun.

FIG. 3 (a) is a plan view showing a structure of first and third electrode elements of the fourth grid, and FIG. 3 (b) is a sectional view thereof.

FIG. 4 (a) is a plan view showing the structure of a second electrode element of the fourth grid, and FIG. 4 (b) is a sectional view thereof.

FIG. 5 (a) is a diagram showing a waveform of a voltage applied to the second electrode element of the fourth grid, and FIG. 5 (b) is a waveform of a voltage applied to the third and fifth grids. FIG.

FIG. 6 (a) is a diagram for explaining the action of the electrode element divided into three parts of the fourth grid when the electron beam is deflected in the horizontal direction, and FIG. 6 (b) is the electron beam in the vertical direction. It is a figure for demonstrating the effect | action of the 3rd-divided electrode element of a 4th grid at the time of deflecting | biasing.

FIG. 7 is a diagram showing a configuration of a monochrome cathode ray tube which is an embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a conventional monochrome cathode-ray tube electron gun.

FIG. 9 is a diagram showing the shape of a beam spot on a phosphor screen of a conventional monochrome cathode ray tube.

[Explanation of symbols]

 10 ... Face plate 11 ... Funnel 12 ... Phosphor screen 13 ... Neck 15 ... Electron gun 17 ... Deflection yoke 22 ... Cylindrical part 23 ... Long cylindrical part 24 ... Electron beam passage hole 25 ... Electrode plate G1 ... First grid G2 ... No. 2 grid G3 ... 3rd grid G4 ... 4th grid G5 ... 5th grid G6 ... 6th grid G41 ... 1st electrode element G42 ... 2nd electrode element G43 ... 3rd electrode element

Claims (1)

Claim: What is claimed is: 1. A cathode and an electron gun in which first to sixth grids are sequentially arranged in the phosphor screen direction from the cathode, and the electron beam emitted from the electron gun is deflected. In a cathode ray tube for displaying an image on the phosphor screen by deflecting by a non-uniform magnetic field composed of a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field generated by a yoke, a third grid and a fifth grid of the electron gun. Are electrodes to which a dynamic voltage that changes in synchronization with the deflection of the deflection yoke is applied, and a fourth grid located between the third and fifth grids is sequentially located from the third grid to a fifth grid direction. It is composed of first, second and third electrode elements, and the first of these electrode elements
The electrode element and the third electrode element have a cylindrical portion and a long cylindrical portion formed at one end of the cylindrical portion and facing each other and having a major axis in the horizontal direction, and the second electrode element has a circular electron beam. A through hole and a pair of electrode plates projecting into the long cylindrical portions of the first and third electrode elements sandwiching the electron beam passing hole from the horizontal direction are formed, and a dynamic that changes in synchronization with the deflection of the deflection yoke. A cathode ray tube characterized by being an electrode element to which a voltage is applied.