| 摘要 |
<p>17 "Colour display tube." A colour display tube comprising in an evacuated envelope 1 an electron gun system 5 of the "in-line" type for generating three electron beams 6, 7, 8 situated with their axes in one plane. The axis of the central beam 7 coincides with the tube axis 9. The electron beams converge on a display screen 10 provided on a wall of the envelope and in the operating display tube they are deflected over said display screen in two mutually perpendicular directions by means of a first and a second deflection field 80, 91, the direction of the first deflection field being parallel to the said plane. At its end the electron gun system comprised curved field shapers 27, 28 for causing the fields described on the display screen by the electron beams to coincide as much as possible. Each field shaper comprises two or more plates 29, 30, 31, 32 of ferromagnetic material situated substantially in the elongation of each other and separated by slots, said plates being symmetrical with respect to the said plane and the central beam axis and the curved field shapers facing the three beams with their concave sides so that the field shapers make the first deflection field at the area of the electron beams pincushion-shaped. At least the plates 29, 32 which are farthest remote from the said plane comprise at their ends remote from the said plane substantially flat plates 33 extending substantially in the direction of the central electron beam. In such a colour display tube the losses in the second deflection field are small and said field is substantially not distorted. The desired pincushion-shaped distortion of the first deflection field in the field shapers is even intensified.</p> |
