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US 5,117,152 AGranted
Cathode ray tube including a magnetic focusing lens
AssigneeU.S. Philips Corporation
InventorsArne L. Duwaer, Willem M. van Alphen
Life of this patent
Estimating the term…
Abstract
A monochrome cathode ray tube including a magnetic focusing device provided with means for generating a static magnetic focusing field. These means surround the neck of the cathode ray tube without contacting this neck, and a system of correction coils for generating an additional focusing field and 2-, 4- and/or 6-pole fields is provided coaxially between these means and the neck of the tube.
Claims13
A monochromatic cathode ray tube comprising:
- a. an envelope including a neck portion containing an electron gun for producing an electron beam and an enlarged portion containing a luminescent screen for producing a spot when impinged by said beam;
- b. a deflection unit disposed around the neck portion for effecting deflection of the electron beam across the screen;
- c. a magnetic focusing device disposed around the neck portion for producing a static magnetic dipole field for focusing the electron beam onto the screen, said device being directly adjacent the deflection unit and being spaced from said neck portion;
- and
- d. a system of correction coil means, each coaxially-disposed between the neck portion and the magnetic focusing device for producing a respective dynamic magnetic multipole correction field in cooperation with the static magnetic dipole field to dynamically correct a specific type of distortion which occurs as the electron beam is deflected across the luminescent screen.
2 more elements
A monochromatic cathode ray tube comprising:
- a. an envelope including a neck portion containing an electron gun for producing an electron beam and an enlarged portion containing a luminescent screen for producing a spot when impinged by said beam;
- b. a deflection unit disposed around the neck portion for effecting deflection of the electron beam across the screen;
- c. a magnetic focusing device disposed around the neck portion for producing a static magnetic dipole field for focusing the electron beam onto the screen, said device being directly adjacent the deflection unit and being spaced from said neck portion;
- and
- d. a system of independent correction coil means, each coaxially-disposed within the magnetic focusing device between said device and the neck portion for producing respective dynamic magnetic multipole correction fields in cooperation with the static magnetic dipole field to dynamically correct a specific type of distortion which occurs as the electron beam is deflected across the luminescent screen, said correction coil arrangements including:
- (1) a first coil means for dynamically correcting focusing of the electron beam;
- and
- (2) a second coil means for dynamically correcting astigmatism of the electron beam.
5 more elements
Dependencies are inferred from the claim text.