Focus flutter prevention in TV receivers and monitors
AssigneeThomson Licensing
InventorIsaac Michael Bell
Life of this patent
Estimating the term…
Abstract
An inventive method for preventing focus flutter display in a TV receiver or monitor includes the steps of amplifying a received signal for driving cathode elements of a cathode ray tube, and delaying initial full amplification of the signal during the amplifying step for a duration sufficient to prevent focus flutter display on the tube. A corresponding inventive kine driver circuit that prevents display of focus flutter includes an amplifier for amplifying and coupling received video signals to cathode elements of a picture tube, and a control circuit for delaying full amplification of the video signals to be fed to the cathode elements for a duration sufficient to prevent focus flutter display on the tube.
Claims9
A kine driver circuit that prevents display of focus flutter comprising:
- cascode amplifiers for amplifying and coupling received video signals to cathode elements of a picture tube;
- and
- a transistor circuit for biasing said cascade amplifiers and delaying coupling of amplified said video signals to said cathode elements for a duration sufficient to prevent focus flutter display on said tube, said transistor circuit including a transistor biased by a voltage divider of first and second resistors coupled to a base terminal of said transistor, and a series combination of a resistor and capacitor coupled in parallel with said first resistor.
A kine driver circuit capable of preventing focus flutter comprising:
- a first power supply;
- amplifiers coupled to said first power supply for driving cathode elements of a picture tube with video signals amplified by said amplifiers;
- and
- a second power supply coupled to said amplifiers and being varied to control timing of when said amplifiers couple amplified said video signals to said cathode elements said second power supply including a transistor having a conducting junction coupled to said amplifiers and a control terminal coupled to a variable voltage divider circuit, said variable voltage divider circuit comprises a voltage divider of first and second resistors, and a series arrangement of a resistor and capacitor coupled in parallel with said first resistor.
In a television receiver or monitor, a kine driver circuit comprising:
- a picture tube having cathode elements and a control grid, said picture tube being susceptible to focus flutter during initial beam current loading of less than fully heated cathode elements;
- and
- a kine driver circuit comprising:
- amplifiers with inputs for receiving respective video signals to be amplified and driving respective said cathode elements with amplified said video signals, and
- a voltage supply circuit for providing a voltage bias of said amplifiers to control currents in said cascode elements such that coupling of said amplified video signals to said cathode elements is delayed for a time period sufficient to prevent said focus flutter, said voltage supply circuit including a voltage divider of first and second resistors coupled in parallel with a series arrangement of a resistor and capacitor.
Dependencies are inferred from the claim text.