US3409791A - Color tube convergence system deflecting beam in two directions with single magnet - Google Patents

Description

Nov. 5, 1968 SHIGEYA ASHIZAKI ET AL 9 COLOR TUBE CONVERGENCE SYSTEM DEFLECTING BEAM IN TWO DIRECTIONS WITH SINGLE MAGNET Original Filed Dec. 14, 1964 2 Sheets-Sheet 1 FIG. l2 PR/Of? ART INVENTORS $0155 ya Alli/29k! ATTORNEYS Nov. 5, 1968 SHIGEYA ASHIZAKI ET AL 3,409,791

COLOR TUBE CONVERGENCE SYSTEM DEFLECTING BEAM IN TWO DIRECTIONS WITH SINGLE MAGNET Original Filed Dec. 14, 1964 2 Sheets-Sheet 2 INVENTORS ms 5; M312 mam #nnu Irma/1:

BY WMM ATTORNEYS United States ABSTRACT OF THE DISCLOSURE A shadow mask-type color image tube comprising three electron guns in an evacuated envelope with one gun being provided with a pair of horizontal deflecting pole pieces and a pair of vertical deflecting pole pieces made of ferromagnetic material. Magnetizing means are arranged outside of the envelope to magnetize both the pair of horizontal deflecting pole pieces and the pair of vertical deflecting pole pieces. The magnetizing means comprises only one magnet so mounted that the magnetic lines of force of the magnet act on both pairs of deflecting pole pieces.

This application is a continuation of application Ser. No. 417,860, filed Dec. 14, 1964, now abandoned.

This invention relates to cathode-ray tube devices, and more particularly to improvements in or relating to those of multielectron-gun type in which electron beams emitted from a plurality of electron guns are converged onto any minute area on the fluorescent screen.

The primary object of the present invention is to provide a cathode-ray tube device in which the horizontal and vertical deflecting pole pieces provided for one of a plu- I rality of electron guns can be magnetized by a single common magnet disposed outside the cathode-ray tube, whereby electron beams emitted from the electron guns are converged onto any minute area on the fluorescent screen.

There are other objects and particularities of the present invention, which will be made obvious from the following detailed description, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of the essential parts of a conventional three-electron-gun cathode-ray tube;

FIG. 2 is a similar view of a cathode-ray tube embodying the present invention.

FIG. 3 is a partial end view of a cathode-ray tube in accordance with the present invention, and

FIG. 4 is a perspective view of a portion of a cathoderay tube in accordance with the present invention.

Generally speaking, in a cathode-ray tube comprising a plurality of electron guns, such as color television receiver tube of three-electron-gun type, all the electron beams emitted from respective electron guns should be converged onto any minute area on the fluorescent screen.

In order to enable such convergence as above-described, ferromagnetic deflecting pole pieces as shown in FIG. 1 have heretofore been provided for electron guns.

In particular, each of three electron guns 1, 2 and 3 has a Y-axis deflecting pole pieces 4, 5 or 6 secured to the forward end of the electron gun,in order to converge the elecron beams emitted from respective electron guns, and at the same time, the focussing electrode 7 of one electron gun, say 1, is provided with X-axis deflecting pole pieces 8 for effecting deflection in the direction perpendicular to the above. To these pole pieces magnetic fields of appropriate strengths are supplied from outside the tube by means of magnets 9 through 12, respectively, correspOnding to deflecting pole pieces 4, 5, 6 and 8 forming substantially four independent magnetic circuits.

Consequently, two of the three electron guns are provided with pairs of Y-axis deflecting pole pieces 5 and 6 only, respectively, but the remaining electron gun I is provided with two pairs of deflecting pole pieces, that is, Y-axis deflecting pole pieces 4 and X-axis deflecting pole pieces 8. As a result, in order to supply appropriate strength of magnetic fields to both deflecting pole pieces 4 and 8, there are required two independent magnets 9 and 12, and in addition, the relative minute adjustment of these magnets is extremely complicated to effect, with considerable skill.

The present invention has succeeded to eliminate such disadvantages as above.

Referring now to FIG. 2, three electron guns 21, 22 and 23 of the cathode-ray tube embodying the present invention, are provided with Y-axis deflecting pole pieces 24, 25 and 26, respectively, at their forward ends, these pole pieces, per sc, being of known construction and function.

According to the present invention, one of these elec tron guns, say 21, is provided with X-axis deflecting pole pieces 27 which are arranged adjacent to the Y-axis deflecting pole pieces 24 coaxially therewith. As a result, while it is necessary to provide two magnets 28 and 29 for supplying magnetic fields to magnetize the Y-axis deflecting pole pieces 25 and 26 respectively, a single magnet 30 can be co-used for supplying magnetic field to energize both of the Y-axis deflecting pole pieces 24 and X- .axis deflecting pole pieces 27, because of the fact that, when the turning of magnet 30 about its axis 31 and the shift of the same in the axial direction of the tube as well as in the direction perpendicular thereto are effected simultaneously, the relative strengths of magnetic field components supplied to the deflecting pole pieces 24 and 27 vary continuously, and consequently, the electron beam is deflected in the direction of resultant vector of the two components of magnetic field, that is the field in the pole pieces 24 and 27. That is to say, the electron beam emitted from the electron gun 21 can the deflected in every direction in appropriate degree.

As has been understood from the foregoing description, according to the present invention, one of a plurality of electron guns, that is provided with horizontal and vertical deflecting pole pieces, is supplied with magnetic field from a single magnet for magnetizing and controlling both of the deflecting pole pieces, by virtue of the fact that they are disposed adjacently to each other, and the electron beams emitted from a plurality of electron guns, respectively, can well be converged onto any minute area on the fluorescent screen. Thus, according to the present invention, such an advantage is obtained as to simplify the convergence adjustment in color television receiver tube.

The present invention is particularly advantageous when practiced in color television receiver tube employing shadow mask, but may also be applied to multielectrongun cathode-ray tubes of other types and cathode-ray tubes for measurement, for effecting adjustment and convergence of electron beams.

What is claimed is:

1. In a cathode-ray tube device comprising an evacuated envelope having a face plate on one end thereof, three electron guns mounted in said envelope to direct three converging electron beams at said face plate, a mask grid having a large number of minute openings and positioned between said electron guns and said face plate for bombarding predetermined areas on said plate with electron beams from said electron guns, a group of minute openings and positioned between said electron guns ner surface of said face plate forming color triads at particular positions defined by the relation between said electron guns and said mask grid, a pair of horizontal deflecting pole pieces and a pair of vertical deflecting pole pieces aligned with the beam path of one of said electron guns, said pairs of horizontal and vertical deflecting pole pieces being formed of ferromagnetic material and being disposed adjacent to each other for adjusting the electron beam of the associated electron gun, and a single magnet movably mounted outside of said envelope for feeding flux adjustable in amount and direction to both pairs of horizontal and vertical deflecting pole pieces, each said pole piece having a flux receiving surface adjacent said magnet whereby magnetic fields are produced to deflect said electron beam in a direction which is the resultant vector of said magnetic fields.

2. A cathode-ray tube device according to claim 1 in which the remaining two electron guns, other than said one electron gun provided with pairs of both horizontal and vertical deflecting pole pieces, are respectively provided with only a single pair of deflecting pole pieces for deflecting the electron beam of the associated electron gun in a single direction.

3. A cathode-ray tube device according to claim 1 in which said single magnet is mounted for at least one of the following movements: shifting in the direction axially of the tube; shifting in the direction perpendicular thereto; and rotation about an axis perpendicular to a tube axis and passing through the center of said magnet.

4. In a cathode-ray tube device comprising an evacuated envelope having a face plate on one end thereof, three electron guns mounted in said envelope each directing an electron beam to converge on said face plate, a mask grid having a large number of minute openings and being positioned between said electron guns and said face plate for bombarding predetermined areas on said face plate with said electron beams, a group of minute areas of red, green and blue light emitting phosphors disposed on the inner surface of said face plate at particular positions defined by the relation bet-ween said electron guns and said mask grid, at least one of said electron guns being provided with a pair of horizontal and a pair of vertical deflecting pole pieces disposed adjacent to each other and in alignment with the electron beam of said gun, said pole pieces being formed of ferromagnetic material, and a single magnet disposed outside said envelope, each said pole piece having a flux receiving surface adjacent said magnet whereby flux from said magnet magnetizes both said pairs of horizontal and vertical deflecting pole pieces provided for said one of said electron guns to deflect the electron beam in adirection which is the resultant vector of the magnetic field produced.

5. In a cathode-ray tube device comprising an evacuated envelope having a faceplate on one end thereof, first, second and third electron guns mounted in said envelope to direct their electron beams to converge on said face plate, a mask grid having a large number of minute openingsand positioned between said electron guns and said face plate for bombarding predetermined areas of said face plate with the electron beams from said electron guns, a group of minute areas of three kinds of phosphors for providing red, green and blue light rays, respectively, disposed on the inner surface of said face plate at particular positions defined by the relation between said electron guns and said mask grid, said first electron gun being provided with a pair of horizontal deflecting pole pieces and a pair of vertical deflecting pole pieces, both pairs of deflecting pole pieces being fonrned of ferromagnetic material, said pairs of deflecting pole pieces being disposed adjacent to each other for adjusting the electron beam of said first electron gun, a single pair of deflecting pole pieces provided for each said second and third electron guns for deflecting their associated electron beams in a single direction, and a single magnet disposed outside said envelope for magnetizing both of said pairs of horizontal and vertical deflecting pole pieces provided for said first electron gun, each pole piece of each of said pairs of deflecting pole pieces having a flux receiving surface adjacent said magnet, said single magnet being movable in at least one of the following directions: axially of the tube; perpendicular to the axis of the tube; and rotatably about an axis perpendicular to the tube axis and passing through the center of said magnet whereby the magnetic flux developed is varied so that the electron beam is defiected in a direction representing the resultant vector of the magnetic fields produced.

References Cited UNITED STATES PATENTS 2,769,110 10/1956 Obert 3l375 X 2,806,164 9/1957 Clay et al 313- X 2,847,598 8/1958 Hughes 3l370 2,923,844 2/1960 Gundert 31377 X ROBERT SEGAL, Primary Examiner.

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