Box-shaped scan expansion lens for cathode ray tube
AssigneeTektronix, Inc.
InventorConrad J. Odenthal
Life of this patent
Estimating the term…
Abstract
A cathode ray tube is provided with a rectangular box-shaped lens intermediate the tube's screen and beam deflection plates for amplifying beam deflections in both the horizontal and vertical axes. In one form, useful in either monoaccelerator or PDA tubes, the lens includes four tubular elements disposed end-to-end and spaced apart a sufficient distance to isolate them electrically. The adjacent ends of each pair of the elements are oppositely curved to provide electron lenses having vertical cylindrical mid-surfaces. The radii of the cylindrical surfaces and the voltages applied to each element are adjusted to provide a lens system that produces minimum distortion and optimum linearity in the resultant display.
Claims13
In apparatus including a cathode ray tube having a target screen, an electron gun for producing an electron beam directed toward said screen, deflection means disposed along the path of said beam for deflecting the beam in two orthogonal directions, and an electron lens system located along said path intermediate said deflection means and screen for amplifying the beam deflections, the improvement wherein
- said system comprises first, second, and third axially aligned tubular elements of rectangular crosssectional configuration, disposed to accomodate the passage of the beam therethrough and spaced apart a sufficient distance to isolate them electrically from one another, each of said elements including beam entrance and exit ends, one pair of opposite sides parallel to one of said orthogonal directions, and another pair of opposite sides parallel to the other of said directions,
- a first pair of flat plates located intermediate said first and second elements, each plate of the pair being disposed in edge adjacent, parallel relation with the corresponding sides of each element's said one pair of opposite sides, and spaced apart therefrom a sufficient distance to isolate them electrically from one another,
- second and third pairs of flat plates located intermediate said first and second elements, each plate of the second pair being disposed in edge adjacent, parallel relation with the corresponding sides of the first element's other pair of opposite sides, and spaced apart therefrom a sufficient distance to isolate them electrically from each other, each plate of the third pair being disposed in edge adjacent, parallel relation with the corresponding sides of the second element's other pair of opposite sides, and spaced apart therefrom, and from the corresponding plates of said second pair, a sufficient distance to isolate them electrically from one another,
- the opposed end edges of each adjacent pair of elements and plates being differently curved in the other of said orthogonal directions to provide a curved electron lens between each such pair upon the application of different electrical potentials thereto,
- said apparatus further including means for applying suitable different potentials to said elements and plates to provide a deflection amplifying lens system that is convergent in one direction and divergent in the other.
In apparatus including a cathode ray tube having means forming a target for an electron beam, means for producing such a beam directed toward said target-forming means, deflection means disposed along the path of said beam for deflecting the beam in two orthogonal directions, and an electron lens system located intermediate said deflection means and target-forming means for amplifying the beam deflections, the improvement wherein
- said lens system comprises successive first, second, third and fourth axially aligned sections disposed to accomodate the passage of the beam therethrough and electrically isolated from one another, each of said sections including a pair of opposed, substantially planar sides disposed parallel to one of said orthogonal directions, and another pair of opposed, substantially planar sides disposed parallel to the other of said directions, the sides of each section having end edges disposed in spaced opposition to corresponding end edges of each adjacent section, with the opposed end edges of sides parallel to at least one of said directions being oppositely curved to form an arcuate gap therebetween, the gaps between two pairs of adjacent sections being curved in one direction and the gap between the remaining pair being curved in the opposite direction,
- said apparatus additionally including means for applying suitable different electrical potentials to said sections to form a plurality of curved electron lenses that act in conjunction to amplify beam deflections in both of said directions.
Dependencies are inferred from the claim text.