Back to results
US 4,734,771 AGranted
Start-up control circuitry for a television apparatus
AssigneeRCA Corporation
InventorsJeffery B. Lendaro, Robert L. Shanley, II, Jack Craft, Michael L. Low
Life of this patent
Estimating the term…
Abstract
A supply voltage is developed in accordance with an on/off control signal of a remote receiver during a start-up interval and during a power-up mode of operation of a television power supply. During a standby mode of operation, the supply voltage is switched off. The supply voltage produces a supply current in an oscillator that produces a signal at a horizontal rate related frequency. The supply voltage also produces a base drive current in a switching transistor of a horizontal driver only during the start-up interval. During a power-up mode, a run supply voltage is coupled to the oscillator and to the driver.
Claims19
A television apparatus power supply comprising:
- a source of an input supply voltage;
- a transformer having a first winding that is coupled to said input supply voltage;
- means coupled to a second winding of said transformer for generating a first supply voltage at a first terminal during operation in a standby mode and during operation in a start-up interval;
- a source of an on/off control signal that is selectively indicative when operation in said standby mode is required and when operation in a power-up mode is required;
- a control circuit responsive to said on/off control signal for generating a signal at a first frequency, said control circuit being energized during said start-up interval from a voltage that is derived from said first supply voltage;
- a first switching transistor responsive to said signal at said first frequency and to said on/off control signal and having a main current conducting electrode that is periodically switched at a rate that is determined by said first frequency signal during operation in each of said power-up mode and said start-up interval;
- means responsive to said on/off control signal and coupled to said first supply voltage for generating at a second terminal a second supply voltage during said start-up interval but not in said standby mode;
- a second switching transistor having a main current conducting electrode that is coupled to said first supply voltage during both said start-up interval and said standby mode and having a control electrode that is coupled to said second supply voltage, said control electrode of said second switching transistor being responsive to the switching of the main current conducting electrode of said first switching transistor for causing said second switching transistor to be conductive during said start-up interval;
- and
- an output stage of said power supply coupled to said main current conducting electrode of said second switching transistor for generating during said power-up mode a third supply voltage that is coupled to said main current conducting electrode of said second switching transistor.
7 more elements
In television apparatus having a power supply including a capacitance for energizing a first load circuit and a first current source for charging said capacitor prior to a start-up interval to a voltage at a level that exceeds a predetermined first voltage level, a start-up circuit, comprising:
- a source of an on/off control signal that is selectively indicative when operation in a power-up mode and when in a standby mode is required;
- means responsive to said voltage in said capacitor and to said on/off control signal for generating a second control signal that enables said power supply to energize said load circuit when said on/off control signal is at a first state that is indicative that operation in said power-up mode is required, provided said level of said voltage in said capacitance exceeds at least a predetermined second voltage level that is lower than said first voltage level, said second control signal disabling said power supply to prevent energizing of said load circuit when said on/off control signal is at a second state that is indicative that operation of said power supply in said standby mode is required, said power supply when enabled drawing a supply current from said capacitance that tends to discharge said capacitance and when disabled said power supply drawing a substantially smaller current from said capacitance;
- means coupled to said capacitance and responsive to the attainment of said second voltage level in said capacitance for disabling said power supply so as to reduce said supply current drawn from said capacitor each time said capacitance discharges to said second voltage level for permitting said capacitance to recharge from said first current source;
- means responsive to said second control signal for generating at a first terminal a first supply voltage when said power supply is enabled that is removed when said power supply is disabled;
- an oscillator having a supply voltage receiving terminal that is coupled to said first supply voltage to form a second load circuit that draws from said first terminal at least a substantial portion of a supply current that is required for operating said oscillator such that when said power supply is disabled said supply current drawn by said oscillator from said first terminal is substantially reduced and when said power supply is enabled said oscillator produces a signal at a first frequency;
- and
- means responsive to said signal at said first frequency and to the energization of said first load circuit for generating a second current that is controlled by said first load circuit to develop a steady state voltage across said capacitance during said power-up mode that prevents said capacitance from discharging.
4 more elements
Dependencies are inferred from the claim text.