Claims
- 1. A color display tube comprising:
- (a) an evacuated envelope having a display window with an inner surface supporting a luminescent display screen;
- (b) an electron gun system for producing central and first and second outer electron beams having their axes lying in a longitudinal plane intersecting the display screen, and for converging the electron beams toward a point of coincidence on said display screen;
- (c) first and second deflection means disposed around the electron beam axes for producing first and second deflection fields for deflecting the electron beams in a first direction perpendicular to the longitudinal plane and in a second direction parallel to said plane, respectively; and
- (d) field shaping means, arranged at an end of the electron gun system from which the electron beams exit, for locally distorting at least one of the deflection fields to augment dynamic convergence of the electron beams such that there is coincidence on the display screen of respective rasters produced by said electron beams;
- characterized in that the field shaping means comprises first and second ferromagnetic plate means arranged symmetrically with respect to both the longitudinal plane and the central beam axis, said plate means being arranged transversely to said longitudinal plane and shaped such that they partially surround the beam axes and distort the first deflection field, where the electron beams enter said field, such that said field is pin-cushioned-shaped, each of said plate means comprising at least first and second circumferentially-spaced plates defining a slot therebetween, and a third slot-covering plate radially spaced from said first and second plates and partially overlapping said plates, said slot-covering plates forming magnetic shunts across the slots covered thereby for shunting the second deflection field and minimizing distortion by said slots of said second deflection field.
- 2. A color display tube as in claim 1 where each of said ferromagnetic plate means comprises first and second circumferentially-spaced plates symmetrically disposed on opposite sides of the longitudinal plane, and where the third plate intersects said plane and is situated symmetrically with respect thereto.
- 3. A color display tube as in claim 1 or 2 where the electron gun system comprises at the end from which the electron beams exit a centering cup having an inner wall against which said circumferentially-spaced plates are disposed and having an outer wall against which said slot-covering plates are disposed.
- 4. A color display tube comprising:
- (a) an evacuated envelope having a display window with an inner surface supporting a luminescent display screen;
- (b) an electron gun system for producing central and first and second outer electron beams having their axes lying in a longitudinal plane intersecting the display screen, and for converging the electron beams toward a point of coincidence on said display screen;
- (c) first and second deflection means disposed around the electron beam axes for producing first and second deflection fields for deflecting the electron beams, the first deflection field having lines of flux extending in a first direction generally parallel to the longitudinal plane, and the second deflection field having lines of flux extending in a second direction generally perpendicular to said plane; and
- (d) field shaping means, arranged at an end of the electron gum system from which the electron beams exit, for causing rasters written on the display screen by the electron beams to substantially coincide;
- characterized in that the field shaping means comprises first and second ferromagnetic plate means arranged symmetrically with respect to both the longitudinal plane and the central beam axis, said first and second plate means being arranged outside the beam paths of the respective first and second beams, each of said first and second plate means being of generally concave form such that it is divergent relative to the longitudinal plane and partially surrounds the respective beam axis;
- said first and second plate means each comprising at least first and second circumferentially-spaced plates defining a slot therebetween and a third slot-covering plate radially spaced from and partially overlapping said plates;
- said circumferentially-spaced plates locally distorting the first deflection field to effect coincidence of the rasters, and said slot-covering plates minimizing distortion by said slots of said second deflection field.
- 5. A color display tube as in claim 4 where each of said ferromagnetic plate means comprises first and second circumferentially-spaced plates symmetrically disposed on opposite sides of the longitudinal plane, and where the third plate intersects said plane and is situated symmetrically with respect thereto.
- 6. A color display tube as in claim 4 or 5 where the electron gun system comprises at the end from which the electron beam exit a centering cup having an inner wall against which said circumferentially-spaced plates are disposed and having an outer wall against which said slot-covering plates are disposed.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8301712 |
May 1983 |
NLX |
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Parent Case Info
This is a continuation of application Ser. No. 607,544, filed 7 May 1984, now abandoned.
US Referenced Citations (5)
Continuations (1)
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Number |
Date |
Country |
Parent |
607544 |
May 1984 |
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