The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 06, 1987
Filed:
Oct. 15, 1985
Hartmut Harlos, Norderstedt, DE;
U. S. Philips Corporation, New York, NY (US);
Abstract
A circuit arrangement for the control of at least one beam current in a picture tube (9) contains a cut-off point control which on the occurrence of a given reference level in the picture signal adjusts the beam current in one sampling interval to a preset value. A trigger circuit (19) and a logic network (22) are provided to prevent picture interference during start-up of the picture tube (9) due to the beam currents which slowly rise as the hot cathodes (8; 801, 802, 803) heat up and due to the cut-off point control which responds only after the build-up of these beam currents. The trigger circuiit (19) suppresses auxiliary pulses used to generate the beam current after the picture tube (9) is turned on and issues a switching signal to close the control loop during the sampling intervals and to release the control of the beam current by the picture signal when the beam current has built up, and the logic network (22) does not release the control of the beam currents by the picture signal until, after the switching signal, a change signal is issued from a change detector (25) indicating that the cut-off point control has responded.