JPH0354827B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a multi-beam color cathode ray tube (CRT) using an in-line electron gun assembly, in particular an improved magnetic shunt therein to equalize raster dimensions in a screen display. It is about providing means.

BACKGROUND OF THE INVENTION A type of cathode ray tube commonly used in color television and related display applications employs an in-line electron gun assembly in which three separate electron beams are emitted in approximately a common plane. In operation, these beams are directed convergingly toward the plane of a multi-aperture shadow mask adjacent to a cathodoluminescent screen that is patterned along the path. As it passes through the apertures in the shadow mask, the focused beam diverges and impinges individually on the screen for each color pattern. The magnetic field of the associated deflection yoke causes the individual beams to scan the screen, resulting in three distinct color raster patterns which together provide the screen display.

Technological advances have resulted in simplified dynamic convergence circuits along with the development of self-convergence yokes with pink distortion correction for use in in-line cathode ray tubes. Typically, this yoke means advantageously uses saddle-shaped horizontal deflection windings and toroidal-shaped vertical deflection windings. The resulting raster patterns sometimes exhibit comatic aberrations because the yoke's magnetic field interacts with each beam, resulting in slightly different sizes of the raster patterns.

To effect coma correction, the prior art has long relied on the positioning of various types and designs of magnetic shunts and/or magnetic shielding means, known as enhancers, relative to the deflection plane to influence the deflection field for the in-line beam. I've acknowledged it.

A recent advance taught by Hughes, US Pat. The idea is to provide some degree of coma correction by positioning it to surround the outer in-line beam.
However, the protrusions on the front surfaces of these opposing shunts are closer to the central beam and therefore have the effect of weakening the yoke-induced horizontal deflection field and strengthening the vertical deflection field.

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide an electron gun assembly with individually configured magnetic shunt means to improve raster comma by better modifying the effect of the deflection field generated by an externally located deflection yoke. An object of the present invention is to provide an improved three-beam in-line color cathode ray tube with enhanced correction. The in-line electron gun assembly emits a central electron beam and two outer electron beams from a convergent cup-shaped electrode member having three apertures located at its ends.
Fixed to the bottom of this cup-like member are two similar generally flat washer-like magnetic shunt elements, oriented such that they face each other, and each magnetic shunt element having a Enclose the opening. The dimensions of the apertures in these magnetic shunt elements are at least approximately equal to the dimensions of the apertures associated with the respective outer beams in the cup-shaped convergence electrodes. Each magnetic shunt element also has a front edge facing toward the central aperture of the convergence electrode. These facing front edges have a concave shape and are opposed to each other to form a pair of cooperating arcuate edges proximate the central aperture and partially surrounding an area around the central aperture. Preferably, the axis of this arcuate edge lies in a common plane coinciding with the in-line plane of the beam. In addition, the arc of the arcuate edge is preferably part of the circumference of a circle that is larger than and concentric with the circumference of the central opening in the convergence electrode.

The magnetic shunt elements of the present invention are individually shaped, dimensioned, and arranged to modify the tail of each yoke field to equalize the size of the rasters generated by the three beams. Modify it as follows.

Optimal form for carrying out the present invention The invention will be explained in detail with reference to the drawings.

1 and 2 show a color cathode ray tube 11 using a plurality of inline beams, which has an axis "A" passing through it, including a neck section 13, a funnel section 15 and a panel section. 17
It has a container made of an integrated material. Second
The figure is a front view of a cathode ray tube, which has a long axis XX and a short axis YY. Therefore, the cross-sectional view in FIG. 1 is taken along the plane of the long axis XX, which serves as a reference.
On the inner surface of the panel is provided a cathode-ray-emitting screen 19 consisting of a repeating array of three color phosphors in distinct stripes or strips parallel to the minor axis Y--Y. Spatially associated with the patterned screen within this panel is a structure 21 having a number of apertures, such as a shadow mask.

An in-line electron gun assembly 23 that emits a plurality of integrated beams is housed within the neck portion 13 of the container, and is configured to emit three individual electron beams 25, 27 in the plane of the X-X axis. and and 29 are formed and rush towards the patterned screen 19. The electron gun assembly 23 includes a plurality of sequentially positioned electrode members, the last of which is an anode 31 and a convergence member 33 having three cup-shaped holes at the end, as shown in FIG. It is shown in Figure 3. Improved magnetic shunting means 35 and 37 according to the present invention are provided within the terminal convergence member and are secured in opposing relationship surrounding the outer beam apertures 39 and 43, as shown in FIG. The significance of these improved magnetic shunting means will be fully explained below.

A convergence or beam adjustment device 45 is provided outside the cathode ray tube neck 13 to surround a portion of the electron gun assembly 23. This beam adjustment device 45 comprises a plurality of adjustable magnetic means, which provide the necessary control magnetic field for the desired beam shift within the electron gun, and which provides the necessary control field to the mask 47 in the center of the screen 19.
is arranged to produce static convergence of the beam in the plane of the beam. The term "static" refers to the path the beam follows when there is no scanning force. As it passes through the mask, the beam diverges slightly and strikes a phosphor layer of the appropriate color on a patterned screen ahead.

When the cathode ray tube is in operation, as the conditioned in-line beams leave the electron gun assembly, these beams are located outside the cathode ray tube enclosure approximately in the area of the interface between the neck portion 13 and the funnel portion 15 of the tube. Self-converging magnetic field deflection yoke 49 located
controlled by a magnetic field generated by a coil. The magnetic fields generated by the toroidal vertical deflection windings and saddle shaped horizontal deflection windings of the yoke 49 and associated circuitry move or scan the conditioned beam in a converged manner horizontally and vertically across the screen. , resulting in a raster pattern 51 centered on three approximately rectangles. It is important that the convergence of the beams must be maintained during the scanning process, also known as "dynamic" convergence. The beam deflection first appears approximately at the deflection plane indicated by D--D in FIG.

An inherent difficulty encountered with in-line cathode ray tubes using self-converging yokes is that the raster formed by the central beam is slightly wider and lower in height than the raster formed by the two side-related beams, resulting in comatic aberration. It is often shown. Since the deflection field at the rear of the yoke extends into the front region of the electron gun assembly, it turns out that a variant improving the rear of the respective horizontal and vertical deflection fields can be implemented in the convergence member 33 of the terminal. are doing.

For a detailed explanation, FIGS. 3 and 4 will be described. The cup-shaped convergence electrode member 33 is shown as having three equally sized in-line apertures, a central aperture 41 and two outer or side-related apertures 39 and 43. two similar substantially flat washer-like magnetic shunt elements 35 and 3 in relation to the externally associated aperture;
7 will be provided. Each magnetic shunt element has a respective aperture 51 and 53, which apertures are at least as large as the aperture 3 associated with the respective outer side of the convergence electrode member 33.
Equal to 9 and 43. These magnetic shunt elements have front edges 57 and 59 facing towards the central opening 41 of the convergence member 33. These front edges 5
7 and 59 have a concave shape and form a pair of arcuate edges 61 and 63. These edges face oppositely towards the central opening 41 and partially enclose an area around the central opening 41 . As shown in the figure, the arcuate edge is a part of the circumference, and the central opening 4
It is larger than the circumference 65 of 1 and is concentric with this, and is represented by the radius "R" which defines the arc 61 of the edge. The axes of the arcuate edges lie in a common plane that coincides with the in-line plane X--X of the aperture of the convergence member.

The concave arcuate edge formed on the front edge of the magnetic shunt element of the present invention is known to provide a deflection field modification that provides improved symmetry and uniform control. The concave symmetry of the magnetic shunt element produces a superimposed magnetic field pattern different from that created by the convex front edge of prior art magnetic shunt means.

For detailed explanation, reference is made to FIG. This FIG. 5 is similar to FIG. 4, but the three electron beams 25, 27 and 29 are shown as a bundle of electrons passing through an aperture in the terminal convergence member 33. As illustrated diagrammatically, the yoke 4
A portion of the rear region of the vertical deflection field 67 of 9 is shunted around the outer beams 25 and 29, the arcuate edges 61 and 63 effecting a concentration of the magnetic flux on the central beam 27 and the raster thereby defined. Increase the vertical dimension of

Similarly, FIG. 6 shows the yoke horizontal deflection magnetic field 69
2, in which the effect on the center beam 27 is reduced due to the magnetic shunting means, which reduces the horizontal width of the center beam raster. Thus, by suitably sizing the magnetic shunt elements 35 and 37, the three color rasters comprising the screen image are equally sized to produce the desired raster pattern 51.

Magnetic shunt elements 35 and 3 provided with apertures
Dimensions consisting of 7 curves, i.e. height “V”, width “W”
and the length of the arcuate edge 61 and the distance "R,r" of this arcuate edge from the axis "A" of the central aperture 41 are all determined empirically to meet the requirements of the particular type of electron gun being considered. It will be done.

To give an example for explanation, it is shown in Figure 4.
Illustrative dimensions of magnetic shunt elements used in multiple low bipotential (Lo-Bi) in-line electron gun assemblies used in 19V90° CRTs are of the following order:

Diameter of terminal convergence member 33: 872 mils (22.15 mm) Diameter of all openings in convergence member: 125
mils (3.18mm) Magnetic Shunt Elements 35, 37 Opening Diameter "0": 125 mils (3.18mm) Magnetic Shunt Elements 35, 37 Height Dimension "V": 312 mils (7.92mm) Magnetic Shunt Width dimension “W” of elements 35, 37: 230 mils (5.84 mm) Diameter “R” of arcuate rim 61: 125 mils (3.18 mm) Thickness of magnetic shunt elements 35, 37: 10 mils (0.254 mm) The magnetic shunt surface element is made of a material with high magnetic permeability, such as "Permalloy 49". This "permalloy"
49'' has a composition of approximately 49% nickel, 48% iron, and the balance consisting of manganese, silicon, and carbon.

The dimensions for illustrating another embodiment of the present invention in a 19V 90° deflection CRT multiple high bipotential (Hi-Bi) in-line electron gun assembly as shown in FIG. 7 are of the following order: .

Convergence member 71 diameter: 872 mils (22.15
mm) Convergence member aperture diameter: 165 mils (4.19 mm) Magnetic shunt element 73, 75 aperture diameter “O”: 165 mil (4.19 mm) Magnetic shunt element 73, 75 height dimension “V” ": 375 mils (9.53 mm) Width dimension "W" of magnetic shunt elements 73, 75: 274 mils (6.96 mm) Diameter "r" of arcuate rim 77: 118 mils (3.00 mm) Magnetic shunt elements 73, 75 Thickness: 10 mils (0.254 mm) The above example illustrates the use of the present invention in a multiple beam low and high dual potential electron gun assembly used in a 19 inch tube. However, the present invention is also applicable to other types of electron gun assemblies, including triple potential focus (TPF) electron gun assemblies. In addition, the present invention provides a 25-inch beam deflection angle of 100°.
Other sizes of cathode ray tubes such as CRTs can also be used.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the beam plane in an in-line color cathode ray tube to which the present invention is applied, FIG. 2 is a front view of the cathode ray tube taken along line 2-2 in FIG. 1, and FIG. 4 is a cross-sectional view of the front portion of an in-line electron gun assembly incorporating the present invention, and FIG. FIG. 5 is an explanatory diagram showing the rear part of the vertical deflection field produced by the magnetic shunt element of the present invention, and FIG. 6 is a diagram showing the rear part of the horizontal deflection field produced by the magnetic shunt element of the present invention. Explanatory diagram showing the modification of , No. 7
The figure is an explanatory diagram of another embodiment of the present invention. 11...Color cathode ray tube, 13...Network section,
15...Funnel part, 17...Panel part, 19
... Screen, 21 ... Structure having multiple openings, 23 ... In-line electron gun assembly, 25,2
7, 29...electron beam, 31...last anode,
33... Convergence member, 35, 37... Magnetic shunt means (element), 39, 43... Outer beam aperture, 41... Center aperture, 45... Convergence or beam conditioning device, 47... Mask, 49
...Magnetic field deflection yoke, 51...Raster pattern (aperture), 53...Aperture, 57, 59...Front edge,
61, 63... Arc, 65... Circumference of central opening, 67
... Vertical deflection magnetic field, 69 ... Horizontal deflection magnetic field, 71
... convergence member, 73, 75 ... magnetic shunt element, 77 ... arcuate edge.

Claims (1)

[Claims] 1. Adopts an in-line electron gun assembly that emits one central electron beam and two outer electron beams into a common plane from a convergence electrode member located at a terminal and having three apertures. and the convergence electrode members are fixed to the convergence electrode members facing each other, surround each of the outer apertures associated with the outer electron beam among the three apertures, and are arranged by externally located deflection yokes. two magnetic shunting means for modifying the effects of the generated deflection magnetic field, each magnetic shunting means having an aperture having dimensions at least approximately equal to the dimensions of said outer aperture;
similar substantially flat washer-like elements, each element having a concave front edge facing towards the central aperture associated with the central electron beam of the three apertures; , forming a pair of cooperating arcuate edges oriented oppositely to each other and adjacent to said central aperture and partially surrounding an area around said central aperture. 2. The color cathode ray tube according to claim 1, wherein the axes of the arcuate edges lie within the common plane. 3. A color cathode ray tube according to claim 1, characterized in that the dimensions of the aperture of the element are equal to the dimensions of the central aperture. 4. The color cathode ray tube according to claim 1, wherein the arcuate edge is larger than the circumference of the central opening and substantially coincides with a part of the circumference of a circle that is substantially concentric therewith.