Tetrode electron gun for electron beam columns
CA 2325653 A1 · Owner: Veneklasen, Lee H. · Inventors: Veneklasen, Lee H.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Conventional electron guns in electron beam columns utilize a thermionic triode configuration. A tetrode (four electrode) gun is described which allows the, adjustment of both variable high brightness and illumination uniformity in the profile of the electron beam. This is achieved by adding an electrostatic focusing, electrode between the cathode and the anode within the electron gun. The focusing, electrode is positively biased to a few keV and allows the image of the cathode to, be focused at infinity. The addition of a focusing electrode enables both variable, brightness and illumination uniformity by adjustment of the bias of a grid which is, mounted below the cathode to maintain …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed November 9, 2000. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 9, 2020.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 9, 2022.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.