JP2001006583A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode-ray tube having improved display quality with no joint between adjacent small pictures. SOLUTION: In this cathode-ray tube, a plurality of electron guns for emitting an electron beam on a phosphor screen and for dividing and scanning the phosphor screen into a plurality of areas are provided within a vacuum envelope. Each electron gun is provided with a cathode for emitting the electron beam and an electron lens having an electrode group disposed with the cathode, the cathode is applied with a picture signal voltage. One of the electrode group has an electrode opening 60 for passing the electron beam through and a recessed part 62 in an approximately rectangular shape. The electrode opening 60 is disposed in the recessed part 62 and the center axis of the recessed part 62 is disposed offset in the direction inverse to the border of the divided areas respective to the center axis of the electrode opening 60. By providing a deflecting part having three recessed parts 62 on the surface on the third grid electrode side of a second grid electrode G2, a deflected amount of the electron beam is corrected to reduce a variation amount of the electron beam reaching point on the phosphor screen to approximately zero according to an amount of the electron beam current.

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,
The present invention relates to a cathode ray tube which scans a single phosphor screen by dividing it into a plurality of regions by electron beams emitted from a plurality of electron guns and connecting small images drawn in each region to form one large screen.

[0002]

2. Description of the Related Art In recent years, various studies have been made on a high-definition picture tube having a high-definition broadcast or a large screen associated therewith. Generally, in order to achieve high resolution of a picture tube, the spot diameter of an electron beam on the phosphor screen must be reduced. On the other hand, conventionally, the electrode structure of the electron gun has been improved or the diameter of the electron gun itself has been increased,
Elongation has been attempted, but sufficient results have not yet been obtained. The biggest cause of this is that the distance from the electron gun to the phosphor screen becomes longer as the tube becomes larger, and the magnification of the electron lens becomes too large.

Therefore, in order to realize high resolution, the distance (depth) from the electron gun to the phosphor screen is required.
It is important to shorten Also, in this case, if the wide angle deflection is used, the magnification difference between the center and the periphery of the screen increases. For this reason, wide-angle deflection is not advantageous for achieving high resolution.

As a cathode ray tube satisfying such demands,
For example, Japanese Patent Application Laid-Open No. 5-36363 discloses that a single phosphor layer is divided into a plurality of regions by using a plurality of electron guns and a plurality of deflection yokes and scanned, and a small image drawn in each region is scanned. 2. Description of the Related Art A cathode ray tube which forms a large screen by being connected is proposed.

However, in the case of such a cathode ray tube in which a video signal voltage is applied to a cathode (cathode) and a magnetic field of a deflection yoke or the like is controlled to scan an electron beam, the amount of electron beam current taken out from the cathode used is limited. If it is changed, the arrival point of the electron beam on the phosphor screen changes depending on the amount of current and the amount of deflection.

Since the anode potential (Eb) is always constant, if the cathode potential (Ek) is changed in order to change the amount of electron beam current, the potential difference between Ek and Eb (hereinafter referred to as Ek-Eb). ) Changes. This Ek-Eb determines the electron beam speed, and
There is a proportional relationship between k-Eb and electron beam velocity.

On the other hand, a deflection yoke for deflecting an electron beam is attached to the neck of the cathode ray tube, and a constant magnetic field is always formed at a constant period in the tube. When an electron beam passes through a magnetic field formed by this deflection yoke,
As described above, when the electron beam speed difference caused by the change of Ek-Eb occurs, the total deflection amount received by the electron beam changes. When such a relationship is expressed by an equation, it is roughly expressed as follows. Deflection amount ∝ 1 / √ (Eb−Ek) In other words, the electron beam deflection amount decreases as the potential difference Ek−Eb increases, for example, as Ek decreases to increase the electron beam current amount. This indicates that the arrival point on the screen changes depending on the amount of electron beam current. In the case of a cathode ray tube in which a phosphor screen is divided and scanned by a plurality of electron guns and a drawn small image is connected to form a single large image, the maximum deflection of each electron gun at a boundary portion between adjacent small images. Since the area comes, when the arrival point of the electron beam changes, the joint between the small images becomes conspicuous, and the image quality is reduced.

[0008]

As described above, a single phosphor screen formed inside a panel is used as a display device having a high resolution, a short depth, a simple structure, and high practicality and industrial value. In the case of configuring a display device that scans by dividing into a plurality of regions, if there is an electron beam arrival point difference due to a change in the amount of electron beam current as described above, there is a problem that a joint between adjacent screens occurs. there were.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to prevent the occurrence of a difference in electron beam arrival point on a screen due to a change in the amount of electron beam current, thereby improving the display quality of a cathode ray. To provide tubes.

[0010]

In order to achieve the above object, a cathode ray tube according to the present invention comprises a vacuum envelope having a panel having an inner surface formed with a phosphor screen having an integral structure, and the vacuum envelope. A plurality of electron guns respectively arranged in the neck of the phosphor screen, and the electron beam emitted from the plurality of electron guns scans the phosphor screen by dividing the phosphor screen into a plurality of regions, The gun has a cathode that emits an electron beam, and in a cathode ray tube that changes the cathode potential to adjust the amount of electron beam current of the electron beam, in synchronization with the change in the cathode potential,
A deflecting unit is provided for deflecting the electron beam in a direction in which a change of the electron beam reaching the screen is eliminated.

According to the cathode ray tube of the present invention, the correction unit uses an electron lens system provided on an electrode constituting an electron lens of an electron gun or a magnetic field system for deflecting an electron beam by a magnetic field. ing.

According to the cathode ray tube configured as described above, the amount of change in the potential applied to the cathode of the electron gun to adjust the amount of electron beam current, that is, the cathode potential (Ek) and the anode potential (Eb) The displacement of the arrival point of the electron beam on the phosphor screen caused by the change in the potential difference between the electron beam and the electron beam can be corrected, and the difference between the arrival points of the electron beam can be almost eliminated. As a result, when the phosphor screen is divided and scanned by the electron beams emitted from the plurality of electron guns and the formed small images are joined to display one large image, the joint between the small images is eliminated and the display is performed. A cathode ray tube with improved quality can be provided.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a cathode ray tube according to an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the cathode ray tube includes a vacuum envelope 10, which includes a panel 12 made of glass,
A glass rear envelope 14 provided opposite the panel and integrally having two funnels 16;
It has. The panel 12 integrally includes a substantially rectangular face plate 18 having a rectangular phosphor screen 15 formed on an inner surface thereof, and a skirt portion 20 erected on a peripheral portion of the face plate.

The phosphor screen 15 extends in the vertical direction, and has a plurality of stripe-shaped three-color phosphor layers emitting blue, fringe, and red light, and a black layer provided between these three-color phosphor layers. And stripes. The phosphor screen 15 is integrated in the entire screen area, and is formed continuously without any joint.

The rear envelope 14 is joined to, for example, frit glass in a state where the rear envelope 14 is in contact with the end surface of the skirt portion 20 of the panel 12. A neck 22 made of glass is joined to the small-diameter end of each funnel 16 and extends parallel to each other. In each neck 22, a horizontal in-line type electron gun 24 for emitting an electron beam toward the phosphor screen 15 is arranged. An auxiliary coil 23 is attached to each neck 22. Further, a deflecting device 28 for deflecting the electron beam emitted from the electron gun 24 is mounted outside each funnel 16.

A substantially rectangular shadow mask 30 in which a large number of electron beam passage holes are formed is disposed in the vacuum envelope 10, and is located opposite to the phosphor screen 15. The shadow mask 30 is supported by the panel 12 via a holder fixed to the mask frame and stud pins projecting from the skirt portion 20 of the panel 12.

In this embodiment, the phosphor screens 15 are arranged in the longitudinal direction (horizontal direction) of the panel 12.
It has two divided areas A and B. These divided areas A and B have the same rectangular shape. And 2
The two necks 22 and the electron gun 24 are arranged such that their central axes coincide with a normal passing substantially through the center of the corresponding divided areas A and B.

In the cathode ray tube having the above-described structure, the electron beams emitted from the two electron guns 24 are deflected by the magnetic fields generated by the corresponding deflecting devices 28, and are deflected by the two magnetic screens of the phosphor screen 15 via the shadow mask 30. The divided areas A and B are scanned horizontally and vertically, respectively. Although the small images drawn on each of the divided areas A and B of the phosphor screen 15 by the divided scanning are separate from each other, they are connected by controlling signals applied to the electron gun 24 and the deflecting device 28, and are connected to each other. One large image is reproduced without interruption over the entire surface of the image.

On the other hand, a three-beam type electron gun 24 is provided in each neck 22. Each electron gun structure 24
As shown in FIGS. 2 and 3, a cathode structure 40 for emitting electrons, and first and second grid electrodes G1 and G for controlling behavior of electrons emitted from the cathode structure.
2, a plurality of grid electrodes such as a third grid electrode G3, a fourth grid electrode G4, a fifth grid electrode G5, and a sixth grid electrode G6. These grid electrodes constitute an electron lens.

The cathode structure 40 includes a cathode sleeve 44 having a disk-shaped cathode 42 provided at one end thereof, and a substantially cylindrical cathode holter 46 disposed substantially coaxially outside the cathode sleeve and supporting the cathode sleeve from outside. And a heater 48 provided inside the cathode sleeve for heating the cathode 42.

The cathode 42 is an impregnated cathode composed of a porous material made of a refractory metal such as tungsten and an electron emitting material impregnated in the porous material. The emission surface 43 emits thermoelectrons. Further, the heater 48 is, for example, a coil formed by winding a rhenium tungsten wire having a predetermined wire diameter by wire drawing, and further using an electrophoretic coating method, a spraying method, an impregnation method or the like to insulate the cathode structure from the cathode structure. Is formed by coating with an Al ₂ O ₃ film.

The electron gun 24 is an electron gun of a composite focus system of a high potential and a unipotential. For example, an operating voltage of 6.3 V is applied to a heater 48 from a heater power supply 50. In addition, the cathode 42
, A video signal voltage of 0 to 200 V is applied from the video signal power supply 52. The first grid electrode G1 is grounded (0 V)
A voltage of 600 to 800 V is applied to the second and fourth grid electrodes G2 and G4 from the grid power supply 54, and a voltage of 5 to 10 V is applied to the third and fifth grid electrodes G3 and G5.
kV, a grid power supply 5 is connected to the sixth grid electrode G6.
A voltage of 8 to 20 to 30 kV is applied.

The cathode 42 and the first and second grid electrodes G
The electrons emitted by the triode consisting of 1, G2
The beam is accelerated and converged by a pre-focus lens unit including the second, third, and fourth grid electrodes G2, G3, and G4 and a main lens unit including the fifth and sixth grid electrodes G5 and G6, and is emitted as an electron beam. You. And
This cathode ray tube is configured to change the potential of the cathode 42 to adjust the amount of electron beam current of the electron beam.

As shown in FIG. 4 as a representative of the second grid electrode G2, each grid electrode is formed in a plate shape, and three electrode openings 60 are formed respectively. These three electrode openings 60 are arranged at equal intervals along the long axis direction H (horizontal axis direction) of the vacuum envelope 10. Also, of the grid electrodes, the second grid electrode G
2, three rectangular recesses 62 are formed. These recesses 62 are formed on the surface of the second grid electrode G2 on the third grid G3 side, and are arranged at equal intervals along the longitudinal direction of the vacuum envelope 10.

One corresponding electrode opening 60 is formed in each recess 62. Also, each rectangular recess 62 is
A direction in which the center axis D in the vertical axis direction is offset in the long axis direction H with respect to the center axis E in the vertical axis direction of the corresponding electrode opening 62, and in particular, is separated from the boundary C between the divided areas A and B. It is formed so that it may be offset and located. These recesses 62 function as a deflecting unit that deflects the electron beam in a direction that eliminates the joint at the boundary between the divided areas according to the cathode potential.

The reason why the deflection unit is provided in the second grid G2 is as follows. That is, as described above, the deflection amount of the electron beam on the phosphor screen is determined by the potential difference (Ek−Ek) between the cathode potential (Ek) and the anode potential (Eb).
It is inversely proportional to b), and becomes smaller as (Ek−Eb) is larger, that is, as the electron beam current amount is larger. The cathode ray tube according to the present embodiment employs a method of adjusting the beam arrival point when the electron beam current amount is large, based on the beam arrival position when the electron beam current amount is small. That is, the electron lens that deflects the electron beam hardly acts when the electron beam current amount is small, and needs a characteristic that strongly acts when the electron beam current amount is large.

In the operation state of the electron gun 24, when the electron beam current amount of the electron beam is small, as shown in FIG. 5A, the crossover position of the electron beam is determined by the first grid electrode G1 and the second grid electrode G2. And between
When the electron beam current amount of the electron beam is large, FIG.
As shown in (b), the crossover position of the electron beam is between the second grid electrode G2 and the third grid electrode G3. The electron beam in the prefocus portion of the electron lens is most susceptible to deflection at the crossover position. Therefore, when the amount of the electron beam current is large, the electron lens strongly acts on the electron beam at a position between the second grid electrode G2 and the third grid electrode G3.

Therefore, according to the present embodiment, a deflection portion having three recesses 62 is provided on the surface of the second grid electrode G2 on the side of the third grid electrode, so that the amount of electron beam current can be increased. By correcting the deflection amount of the electron beam, the change amount of the electron beam arrival point on the phosphor screen can be made substantially zero. That is, the arrival point of the electron beam on the phosphor screen can be deflected in a direction to eliminate the joint of the divided screen boundary according to the amount of the electron beam current. This makes it possible to obtain a cathode ray tube capable of displaying a continuous screen with high quality without a break or overlap at the boundary of the divided screen.

FIG. 6 shows the change in the arrival point of the electron beam along the major axis direction H when the current amount of the electron beam changes from 0.1 mA to 3.0 mA with reference to the arrival point at 0.1 mA. The electronic lens system A according to the present embodiment is compared with the conventional system (without correction). The electron beam arrival point was measured at a point 160 mm away from the center of the phosphor screen along the long axis direction H.

In the conventional method, the change amount of the electron beam arrival point increases in accordance with the increase of the electron beam current amount, whereas according to the present embodiment, the electron beam arrival point hardly changes. I understand that there is no.

In the above-described embodiment, the concave portion 62 is formed in the grid electrode as the deflecting portion. However, the present invention is not limited to this, and the deflecting portion may be a magnetic field attached to the neck and deflecting the electron beam in the horizontal direction. The auxiliary coil 23 generated,
Alternatively, a deflection device 28 for electron beam scanning may be used.

FIG. 7 shows a waveform of a current applied to a coil that scans an electron beam in a seam direction of an image when the electron beam is deflected by using the auxiliary coil 23 or the deflecting device 28. It is shown along the axial direction H. After adjusting the arrival point of the electron beam on the screen based on the case where the current amount of the electron beam is small in the entire screen, all rasters are displayed in a state where the electron beam current amount is large in the entire screen. The output state is shown.

Such a waveform is obtained when the same potential difference (Ek-Eb) is applied to the entire screen area. Since the deflection amount becomes larger in the peripheral portion of each divided screen, the difference in the arrival point of the electron beam is also reduced. It increases in proportion.

According to another embodiment, when (Ek−Eb) at each position changes, the correction current amount is controlled based on the curve of the applied current. That is, when displaying a high-brightness (high current amount) image, the correction current may be increased, and when displaying a low-brightness (low current amount) image, the correction current may be reduced.

Changing the deflection in synchronization with the screen brightness (cathode potential) is a necessary correction in the vicinity of the seam of the screen, and is not necessarily required in other areas as in the conventional cathode ray tube. Therefore, the region synchronized with the cathode potential may be determined in consideration of the scale and cost of the driving circuit for forming the correction current, and it is not always necessary to perform the correction in synchronization with the cathode potential over the entire screen.

Whether the correction current is supplied to the correction coil 23 having a neck or to the deflection device 28 may be determined in consideration of practicality. The same operation and effect as the embodiment can be obtained.

In FIG. 6, a characteristic line B shows the characteristics of the magnetic field system according to the other embodiment. As can be seen from the characteristic line B, in the other embodiments as well, the change amount of the electron beam arrival point can be made substantially zero with respect to the increase in the electron beam current amount, and as a result, the distance between the divided images can be reduced. It is possible to obtain a cathode ray tube in which the joints are inconspicuous and excellent in display quality.

It should be noted that it is also possible to use a speed modulation (contour enhancement) coil widely used in a conventional cathode ray tube. Further, when it is difficult to superimpose the correction current on the deflection current of the deflection device due to impedance mismatch between the circuit side and the load side, the correction coil is wound around the deflection coil, and the deflection current is magnetically generated. And the correction current.

Further, the present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, in the embodiment of the system in which the position of the electron beam arrival point is corrected using an electron lens formed by the electrodes in the electron gun, the electron gun of the cathode ray tube is a composite electron gun of high potential and unipotential. However, the present invention is not limited to this, and a unipotential type electron gun, a high potential type electron gun, a high bipotential type electron gun,
The present invention is also applicable to a cathode ray tube having a tri-potential type electron gun, a high uni-potential type electron gun, and the like. The electron gun is not limited to the horizontal in-line type, but may be a vertical in-line type.

Further, the formation method and arrangement position of the electron lens used in the electron gun can be changed as required, and a new electrode such as an astig electrode can be added, and the invention can be applied between other electrodes. An electron lens system such as electric deflection may be used.

In the above embodiment, the number of screen divisions has been described as two. However, the number of screen divisions is not limited to this, and the number of screen divisions can be increased as necessary. In this case, it goes without saying that the number of electron guns also increases according to the number of divisions. The screen may be divided in the vertical direction. In this case, the same effect can be obtained.

In addition, the present invention is not limited to the above-described color cathode ray tube, but can be applied to other types of cathode ray tubes such as a monochrome cathode ray tube and a beam index type cathode ray tube.

[0043]

As described above, according to the present invention, the point at which the electron beam reaches the screen is deflected in the direction to eliminate the joint at the boundary of the divided area in synchronization with the cathode potential of the electron gun. Cathode potential Ek and anode potential E
The present invention provides a cathode-ray tube in which the arrival point of an electron beam on a phosphor screen is prevented from fluctuating according to the amount of electron beam current caused by a change in the potential difference from b, and the display quality is improved without any connection between adjacent small images. can do.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cathode ray tube used for a cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a side view schematically illustrating a cathode structure of the electron gun in the cathode ray tube, partially cut away.

FIG. 3 is a diagram schematically showing a cathode structure and a grit electrode of the electron gun.

FIG. 4 is an enlarged plan view and a perspective view showing a third grid electrode of the electron gun.

FIG. 5 is a diagram schematically showing a state of an electron beam from a cathode to a third grid electrode in the electron gun, when the current amount is small and when it is large.

FIG. 6 is a diagram showing a relationship between an electron beam current amount and an electron beam arrival point change amount in the cathode ray tube in comparison with a conventional cathode ray tube.

FIG. 7 shows a horizontal direction of a current applied to a coil when a deflection device or a correction coil mounted on a neck deflects an electron beam in a cathode ray tube according to another embodiment of the present invention. The figure which shows the example of a waveform.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Vacuum envelope 12 ... Panel 14 ... Rear envelope 15 ... Phosphor screen 16 ... Funnel 22 ... Neck 23 ... Correction coil 24 ... Electron gun 28 ... Deflection device 40 ... Cathode assembly 42 ... Cathode 60 ... Electrode opening 62 recesses G1 to G6 first to sixth grid electrodes

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Nishimura 1-9-2 Hara-cho, Fukaya-shi, Saitama Prefecture Inside the Toshiba Fukaya plant (72) Inventor Hiroki Murata 1-9-1-2 Harara-cho, Fukaya-shi, Saitama No. F-term in Toshiba Fukaya Plant (reference) 5C041 AA03 AB05

Claims (6)

[Claims] 1. A vacuum envelope having a panel in which a phosphor screen having an integral structure is formed on an inner surface; and a plurality of electron guns respectively disposed in a neck of the vacuum envelope. While scanning the phosphor screen by dividing the phosphor screen into a plurality of regions by electron beams emitted from a plurality of electron guns, each of the electron guns has a cathode for emitting an electron beam, and changes a cathode potential. A cathode ray tube for adjusting an electron beam current amount of the electron beam, comprising a deflecting unit for deflecting the electron beam in a direction in which a change in a screen arrival point of the electron beam is eliminated in synchronization with a change in the cathode potential. A cathode ray tube characterized by the above-mentioned. 2. The cathode ray tube according to claim 1, wherein each of said electron guns includes an electron lens provided alongside said cathode and including an electrode constituting said deflection section. . 3. The electrode of each of the electron guns has an electrode opening through which an electron beam passes, and the deflecting portion has a substantially rectangular recess formed in the electrode. Is provided in the recess, and
3. The cathode ray tube according to claim 2, wherein the recess has a central axis offset from a central axis of the electrode opening. 4. The cathode ray tube according to claim 3, wherein the recess is provided in a direction opposite to a boundary portion of the divided region with respect to the electrode opening. 5. The apparatus according to claim 1, wherein the deflection unit includes a correction coil mounted on the neck and deflecting the electron beam by a magnetic field in synchronization with the change in the cathode potential. A cathode ray tube as described. 6. The vacuum envelope includes a plurality of funnels each connected to the neck, and each of the funnels is provided with a deflecting device that scans an electron beam emitted from the electron gun. 2. The cathode ray tube according to claim 1, wherein the device comprises the deflecting unit that deflects the electron beam by a magnetic field in synchronization with the change in the cathode potential.