EP 0283941 B1 19930609 - CATHODE RAY TUBE HAVING AN ELECTRON GUN CONSTRUCTED FOR READAY REFOCUSING OF THE ELECTRON BEAM
Title (en)
CATHODE RAY TUBE HAVING AN ELECTRON GUN CONSTRUCTED FOR READAY REFOCUSING OF THE ELECTRON BEAM
Publication
Application
Priority
- JP 7125087 A 19870325
- JP 7125187 A 19870325
- JP 7125387 A 19870325
Abstract (en)
[origin: EP0283941A2] A cathode ray tube comprises a series of quadrupolar lenses for focusing a beam of electrons, emitted from a cathode at one end of an evacuated envelope under the control of a control electrode, at a target screen at the other end of the envelope. After having been focused at the target by adjustment of electric potentials on the quadrupolar lenses, the electron beam will defocus upon change in a potential on the control electrode because then the crossover or initial focusing point of the electron beam will be displaced along the central axis of the envelope. With a view to ready refocusing of the beam at the target, a refocusing lens is provided between the crossover point and the quadrupolar lenses for providing a convering lens action of radial symmetry about the envelope axis. The beam can be refocused through adjustment of a single potential on the refocusing lens rather than through adjustment of several different potentials on the quadrupolar lenses.
IPC 1-7
IPC 8 full level
H01J 29/62 (2006.01); H01J 31/12 (2006.01)
CPC (source: EP)
H01J 29/62 (2013.01); H01J 31/121 (2013.01)
Designated contracting state (EPC)
FR NL
DOCDB simple family (publication)
EP 0283941 A2 19880928; EP 0283941 A3 19890726; EP 0283941 B1 19930609
DOCDB simple family (application)
EP 88104288 A 19880317