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US 6,211,629 B1Granted
Cut-off level setting
AssigneeU.S. Philips Corporation
InventorsDirk J. A. Teuling, John H. P. Moors
Life of this patent
Estimating the term…
Abstract
The cut-off level (Vcod) of a drive signal (Vd) of a cathode ray tube (3) is (Ib1, Ib2) occurring at these two levels (Vd1, Vd2).
Claims8
A cut-off level setting device comprising:
- drive means for successively supplying a first and a second video drive voltage level to a control electrode of a cathode ray tube to generate a first and a second beam current, respectively, and for supplying a first and a second measurement signal representing the first and second beam currents, respectively;
- and
- control means for supplying a control signal to the drive means to set a cut-off drive voltage level at which a beam current is just about to flow in the cathode ray tube;
- characterized in that the control means comprises calculation means for calculating the cut-off drive voltage level using a mathematical formula defining the cut-off drive voltage level as a function of the first and second drive voltage levels and the first and second measurement signals.
1 more element
A method of setting a cut-off level comprising the steps:
- successively supplying a first and a second video drive voltage level to a control electrode of a cathode ray tube to generate a first and a second beam current, respectively, and supplying a first and a second measurement signal representing the first and second beam currents, respectively;
- and
- generating a control signal for controlling the drive means to set a cut-off drive voltage level at which the beam current is just about to flow in the cathode ray tube, characterized in that the generating step comprises the step:
- calculating the cut-off drive voltage level using a mathematical formula defining the cut-off drive voltage level as a function of the first and second drive voltage levels and the first and second measurement signals.
1 more element
A display apparatus with a cathode ray tube and a cut-off-level setting device, said cut-off-level setting device comprising:
- drive means for successively supplying a first and a second video drive voltage level to a control electrode of the cathode ray tube to generate a first and a second beam current, respectively, and for supplying a first and a second measurement signal representing the first and second beam currents, respectively;
- and
- control means for supplying a control signal to the drive means to set a cut-off drive voltage level at which a beam current is just about to flow in the cathode ray tube, characterized in that the control means comprises calculation means for calculating the cut-off drive voltage level using a mathematical formula defining the cut-off drive voltage level as a function of the first and second drive voltage levels and the first and second measurement signals.
Dependencies are inferred from the claim text.