DE2428047A1 - CATHODE RAY TUBE - Google Patents

Description

It 2911

CORPORATION,

Tokyo / Japan

cathode ray tube

The invention relates to a cathode ray tube, the bulb carries an applied fluorescent screen. In particular The invention relates to a cathode ray tube of the type mentioned, in which the deflection of the electron beam caused light spot distortion is compensated.

It is known that in cathode ray tubes, especially in cathode ray tubes with wide angle deflection, the deflected Electron beam is distorted in cross section by the magnetic deflection field. When such a thing occurs deflected electron beam with a distorted cross-section on the luminescent screen are in certain areas of the The screen gets heavily distorted light spots »The distortion can be so strong that in certain areas a noticeably increased current density as a result of the distortion

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emergence. In such light leak areas with increased Current density, the saturation limit of the luminosity of the phosphor is easily reached. Under these sediments generated images have a poor image quality on. Because of this distortion caused by the magnetic deflection field, the light spot is in the edge areas of the screen formed in the form of a long, laterally warped oval, while the light spot in the central area of the screen has the desired circular shape.

Various methods have been proposed to compensate for this spot distortion. So is for example known to stretch a magnetic Cuadrupole field on the bulb neck of the cathode ray tube, which the beam cross section corrected. The current generating the magnetic field in the quadrupole arrangement becomes synchronous with the Ablehkstrom controlled. There is also a corresponding electrostatic quadrupole arrangement on the focusing electrode of the electron gun known in the tube, which corrects the beam cross-section with the help of an electric field.

The disadvantage of these known devices is their relatively high power consumption, so that they can be used in practice have hardly found entrance.

It is therefore an object of the invention to provide a cathode ray tube in which the deflection caused by the deflection Spot distortion is corrected by an improved system.

Another object of the invention is to provide a cathode ray tube having an improved system for Compensation of the light spot distortion caused by the beam deflection, the system in particular a should have low power consumption.

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Another object of the invention is a cathode ray tube of the type mentioned, in which the distortion compensation takes place electrostatically and magnetically.

The invention is therefore based on the object the technology and in particular a cathode ray tube of the type mentioned with a system "to create that the light spot geometrically over the entire screen surface able to represent correctly corrected, the compensation system should have an extremely low power consumption.

To solve this problem, a cathode ray tube of the type mentioned is proposed, which is characterized . is through (a) a beam generator that emits at least one electron beam in the direction of the screen, (b) a beam deflection * which moves the beam to scan the Deflects the screen, (c) an electrostatic beam control arranged according to the beam path for deformation of the electron beam cross-section to compensate for the distortion of the light spot shape caused by the deflection on the screen impinging beam in the edge areas of the screen and (d) a magnetic beam control also arranged according to the beam path for additional dynamic deformation of the electron beam cross-section depending on the deflection to compensate for the distortion caused by the electrostatic beam control the shape of the light spot of the beam striking the screen in the central area of the screen.

The subject of the invention is therefore a cathode ray tube, in which at least one electron beam is deflected so that it has a fluorescent screen to generate an image scans on this screen, the cathode ray tube

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contains a device for the electrostatic beam control for influencing or deformation of the beam cross section to deform the electron beam cross-section in such a way that AEIE distortion of the shape is compensated _f of the light spot in the peripheral areas of the screen that is caused by deflection, and wherein said cathode ray tube further comprises Device for magnetic beam control contains, which can deform the beam cross-section dynamically urfcer guidance of the deflection in such a way that the distortion of the light spot caused by the electrostatic beam control is compensated in the central areas of the screen.

The invention is described below on the basis of exemplary embodiments in conjunction with the drawings. It demonstrate:

Fig. 1

typical schematic representation comas without cross correction ·

Fig. 2

typical in schematic representation Spot distortion at Partial correction;

Fig. 3

in a schematic representation the contours of ideal or corrected light spots ;

Fig. 4

in a schematic representation a cross section through the cathode ray tube the invention;

Figures 5A, 5B, 6A, 6B, 7A and 7B

partial illustration of the invention

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Positions of an embodiment of the invention;

Pig _o 3 in a schematic representation

Embodiment of the magnetic control of a cathode ray tube of the invention and

fig. 9 is a schematic representation of FIG

Cross-sectional deformations of the electron beam in a tube of the invention.

In the cathode ray tube of the invention, there are electrostatic ones Device that creates an electric control field and a magnetic device that creates an additional Magnetic field generated in the electron gun or on the flask neck to control the shape of the cross section of the electron beam, the beam cross-section is corrected so that the distortion of the light spot over the entire screen area of the cathode ray tube is compensated.

Without a compensation device, the light spots show on the phosphor screen 1 (Fig. 1) in the edge areas Distortions, as shown for the light spots 2b. This is corrected by the distraction of the beam caused distortion of the light spot by a predistortion of the cross section by the electrical Corrected the control field that the beam traverses before entering the deflection field. After going through the control field the beam is shaped by the combined effect of both fields in such a way that those in the edge areas of the The luminous spots 2b generated by the screen are circular (FIG. 2). However, due to this pre-deformation of the beam cross-section

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also the light spot in the central area of the screen 1 is misplaced. It has the oval-distorted shape shown in FIG. 2 for the luminous spot 2a. To compensate for this secondary distortion the rays directed onto the central area of the luminescent screen are passed through before they hit the luminescent screen Additional magnetic field arranged separately from the electrostatic field is additionally deformed in the cross-section in such a way that the The light spot is also circular in the central area of the screen 1. In this way, the light spot 2a or 2b in the "shown in Fig. 3" are kept circular over the entire area of the luminescent screen.

A preferred exemplary embodiment of the invention is described in connection with FIGS. 4-9. The chosen Embodiment of the cathode ray tube of the invention is a color television tube with multiple electron beams, generated in a single electron beam gun. The electron beams intersect in the optical center a known electronic main lens. the Rays leaving the center divergent are converged on the phosphor screen by convergence deflectors bundled.

Referring to Fig. 4, there is shown a cathode ray paint tube of the invention. The single electron gun 4 which generates a plurality of beams is arranged in the neck of the piston 3. The deflection yoke 5 is located around the piston collar. The piston is made of glass. The electron gun is of the equipotential type, the cathodes K, K and K of which are arranged in a common plane in the glass bulb 3. Common grids G to Gr are provided in the glass bulb 3 along a common axis for the cathodes arranged in the order K, K and K. The deflection or convergence device C consists of four deflection plates E, P,, Q ₌ and Q. The distraction

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is arranged after the fifth grid Gj-. _{The electron beams B 1} B and 3 emitted by the cathodes K, K and K, run through the associated bores in the first grid G and in the second grid G ₂ and are then guided so that they are in the optical center of the main electron lens

L cut. This lens L is essentially through the m m

third grid G ₀ , the fourth grid G. and the fifth grid G ₁ . educated. The rays leaving the lens pass between the baffles Q and P, P and P, and P, and respectively

a a a .ο χ)

Q, a. After a given distraction, they converge on a color stripe phosphor screen.

According to the invention in connection with the electron gun created an electrostatic beam control, which to compensate for the beam cross-section distortion an electrical Control field generated. This compensates for the distortion of the light spot that occurs in the edge areas of the screen. The compensation takes place in such a way that the light spot has a predetermined shape, preferably a circular shape, accepts. Furthermore, according to the invention, a magnetic one Beam control 6 arranged around the neck of the glass bulb outside, which can generate a magnetic.Steuerfeld. This magnetic control field is used to compensate for the distortion of the light spot in the center of the screen. Such Distortion of the light spot in the center of the screen is caused, for example, by the electrical control field. The magnetic control field is designed in such a way that the light spot also has the desired contour in the center of the screen has, is usually circular. The electric control field is used to prevent the electron beams from entering the Deform the deflection field so that its cross-section is an elongated oval. The deformed elongated oval in cross-section in this way Electron beams pass through the deflection field and are thus deformed in such a way that the light spot enters the Edge areas of the screen a given, usually

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has a circular shape. Without this pre-deformation, the light spot in the screen edge areas would not be round, but elongated oval. This electrical control field can be generated in a simple manner so that the focus electrode or the fourth grid G. of the electron gun 4 is cup-shaped or cylindrical with an elongated oval cross-section, the long axis of the oval or the ellipse in of the type shown in Fig. 5A may be vertical or may be horizontal in the type shown in Fig. 5B. When the cross section of the cup-like or cup-shaped fourth grid G, in the embodiment shown in Fig. 5A, a standing oval is, is set the Strahlfokussierbedingung as a focus, while in the other case, when the cross section of the becherför.nigen fourth grid G, in The shape of a lying oval of the type shown in FIG. 5B is selected, the beam focusing condition is set to be over-focusing. The fourth grid G. of the equipotential cathode forms an electrostatic converging lens. The cross section 2 of an electron beam passing through the fourth grid G. is given an oval cross section in the manner shown in FIG. The electrons, which are located in the beam cross-section 2 in the area of the points A- and A "in the direction of the short axis of the cross-section of the grid G, are exposed to a relatively strong electric field and are accordingly relatively close to at a point f- fourth grid G. focused. Electrons of cross-section 2 in the area of points B, and B-, on the other hand, which are located in the area of the long cross-sectional axes of fourth grid G. , are only exposed to a relatively weak electric field and are therefore _{focused at a point f 2} , which is wider than the focal point f, from the fourth grating G. is removed. The shape of the cross section 2 * of the electron beam between the fourth grid G. and the focal points f

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corresponding shape compressed. The shape of a cross-section 2 "of the electron beam behind the focal points f 1 and f", the cross sections of the electron beam in the overfocal region, also has the shape of an elongated oval, but the long and short axes are essentially perpendicular to the long and short axes of the cross-section of the fourth grid G. If the fourth grid G. has the shape of a lying elongated oval and the electron beam is overfocused, an electron beam cross-section in the form of an upright oval of the type shown in FIG obtain. On the other hand, if the fourth grating G. is designed so that its cross section has the shape of a standing, elongated oval, and the focus conditions for the electron beam are set so that it is underfocused, a beam spot or beam cross section is obtained which also has the shape of a has upright oval with its long axis. In both cases, the light spots or the beam cross-sections can be compensated so that they are circular in the edge areas of the screen on the luminescent screen 1, but in the center of the screen 1 in the manner shown in FIG. 2B the shape of an upright with the long axis Have ovals.

The electrical control field can, however, also be achieved by changing the shape of the third grating G ₃ or the fifth grating G _1, which can be designed, for example, as electronic diverging lenses. The third grid G ₃ can be cup-shaped, as shown in FIG. Alternatively, the grating may be formed as in the embodiment shown in Figure 6B _o way that your grid G ^ facing end surface perpendicular

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Slots 8, 8, 8 and 8 in the shape of rectangles for the tr g r

Passage of electron beams B,, B and B,

r> g r

If the lying rectangular slot 7 is used jointly for the three beams, then with Unterfokussxerenden Conditions to be worked. If, on the other hand, the three upright verticals associated with the three rays Slots 3, 8 and 8 are provided, overfocusing conditions must be used. Because the third Grating G_ is a concave lens electrostatically, the astigmatism generated in this case is with respect to the In connection with FIG. 9, the conditions for the convex lenses are reversed. The cross section of the light spot becomes an upright oval under underfocusing conditions, but under overfocusing conditions to the lying oval.

The third and fifth grids G- and G ^ can, however, also be cylindrical with compressed cross-sections, either in the manner shown in FIG. 7A as a lying oval or in the manner shown in FIG this form generate the electric control panel of the invention. The grids G _{1 and G 1 can be} formed independently of one another or together, individually or in combination in the manner shown in FIGS. 7A or 7B. In the case of a lying oval cross-section of the type shown in FIG. 7A, underfocusing must take place, while with a standing oval of the type shown in FIG. 7B, over-focusing must be carried out. The conditions correspond to the relationships described in connection with FIGS. 6A and 6B.

At least theoretically, that can correspond to that shown in FIG. 2 Correction required electron beam cross-section can also be generated in such a way that the beam diaphragms in the first grid G-, or in the second grid G ~ with an oval

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Cross-section or the emitting cathode surface can be oval.

To generate the magnetic control field, a magnetic quadrupole yoke is used, the principle of which is designed Shown in Fig. 8 is the magnetic cuadrupole device consists of an annular magnetic core 10 with the four poles 10a, 10b, 10c and iod, which are connected to the ring 10 protrude inwardly opposite each other in pairs and alternating in circumferential order magnetic north poles and Form south poles. The core 10 is surrounded by the correction coil 11. When in the coil 11 via the terminals t a Current in the manner shown by the arrows in FIG flows, the cross section 2 of an electron beam is deformed in such a way that it is in the direction of the X axis bulged or stretched and in the direction of the Y-axis is compressed. The electron beam thus has an oval cross-section with a long horizontal axis. at Reversing the direction of current in the coil 11 will also reverse the distortion of the electron beam "so that this receives a cross-section in the form of an oval standing with its long axis upright. The compression ratio of the electron beam cross section is dependent on the current intensity in the correction coil 11. In the device of the Invention may be one or more of these magnetic Quadrupoles are used.

According to the invention, the correction coil 11 of the magnetic Quadrupole 9 impressed a current with a predetermined parabolic waveform synchronously with the deflection current of the electron beam. This will change the shape of the light spot dynamically compensated in the luminescent screen center or the cross section of the electron beam. The one through the electric Control field for correction of the light spot distortion in the

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Edge areas of the screen produced astigmatism, the leads to an oval elongation of the light spot in the direction of the Y-axis, is in this way for the central areas of the screen balanced.

By deforming the electron beam cross-section by means of an electric control field before the beam is deflected, also in the edge areas of the screen a circular shape or a shape corresponding in some other way to a predetermined shape Luminous spot preserved. The result of this type of compensation in the central area of the luminescent screen through the correction The distorted light spot generated by the electrical control field is additionally corrected in an additional Magnetic field balanced. The light spot distortion generated by the deflection yoke is therefore via the entire screen area fully compensated, for which the device of the invention only an extremely small additional Power consumption required. The reason for the low power consumption of the device of the invention lies in the fact that to compensate for the light spot distortion in the edge areas essentially geometric measures are used and the magnetic quadrupole 9 for the light spot has practically no power consumption in these areas. In the central areas, only lower services are required for cross-section correction. The magnetic one Quadrupole only corrects the beam in these central areas, so it needs a correction for this only a very low power consumption. This combination results in an extremely low total power consumption Correction of spot distortion needed across the entire screen.

The embodiment described relates to a cathode ray color tube in which a single electron beam canon multiple electron beams are generated. the

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Invention can of course also for conventional Cathode ray color tubes can be used.

After taking note of the "description, the person skilled in the art can make a large number of modifications and without inventive step Make adjustments to special conditions.

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Claims (1)

Claims l.yCathode ray tube, the piston of which has an applied Bearing fluorescent screen, characterized by (a) a beam generator., the at least one electron beam emitted towards the screen, (b) a beam deflection that deflects the beam to scan the screen, (c) one arranged in accordance with the beam path electrostatic beam control to deform the electron beam cross-section to compensate for the Distortion caused by the deflection of the light spot shape of the incident on the screen Beam in the edge areas of the screen and (d) a magnetic beam control, also arranged according to the beam path, for additional purposes dynamic deformation of the electron beam cross-section according to the deflection for Compensation of the distortion of the light spot shape caused by the electrostatic beam control of the ray hitting the screen in the central Area of the screen. 2. Cathode ray tube according to claim 1, characterized in that the electrostatic beam control within of the tubular piston is arranged between the beam generator and the deflector, and that the magnetic beam control is arranged outside the tubular bulb between the radiation generator and the deflection " 3. A cathode ray tube according to claim 2 characterized in _t, 409881/1003 that the electrostatic jet control is tubular Electrode with an oval cross-section contains, which with a voltage of a predetermined potential .with the formation of an electric lens field for focusing of the electron beam is applied. 4. Cathode ray tube according to claim 3, characterized in that the tubular electrode with an oval cross-section the middle of three electrodes lying one behind the other in a row with a common axis for generating the electric lens field is. 5. Cathode ray tube according to claim 3, characterized in that that the tubular electrode with an oval cross-section is made up of a series of three one behind the other Electrodes with a common axis for generating an electrical lens field on one of the two side electrodes is. 6. Cathode ray tube according to claim 2, characterized in that that the electrostatic beam control has a cup-shaped electrode with a rectangular There is an opening at the bottom through which the electron beam can pass, and that this electrode is connected to a Voltage of a predetermined potential is applied, so that it can create an electron lens field for focusing the electron beam. 7. Cathode ray tube according to claim 6, characterized in that that the cup-shaped electrode is made up of three electrodes lying one behind the other in a row with a common Axis for generating an electrical lens field is one of the two outer electrodes. o. cathode ray tube according to one of claims 1 to 7, 409881/1003 characterized in that the magnetic beam steering contains a quadrupole, which consists of a magnetic core and a coil around it, whereby the coil is guided by the Äblenkstrornes and can be supplied with current synchronously with it. 9. Cathode ray tube according to claim 8, characterized in that the magnetic core is annular and around the neck, preferably near the collar, of the tubular piston. 409881/1003