Symmetry control circuit and method
January 31, 2014. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesPower supply for a high intensity discharge or fluorescent lamp Two-wire electronic dimming ballast for fluorescent lamps Two-wire electronic dimming ballast for gaseous discharge lamps Electronic ballast for gaseous discharge lamps Regulated switched power circuit with resonant load Resonant inverter having frequency control Fluorescent lamp controllers Controlled series-resonance-loaded ballast Lamp starting and operating procedure in electronic ballast Circuit for driving a gas discharge lamp load InventorsAssigneeApplicationNo. 190746 filed on 01/31/1994US Classes:315/307, Automatic regulation315/207, Discharge device and/or rectifier in shunt to the load device315/226, Plural periodic switches or multiple contact periodic switch315/244, Inductance in the condenser circuit315/308Regulator responsive to plural conditionsExaminersPrimary: Pascal, RobertAssistant: Philogene, Haissa Attorney, Agent or FirmForeign Patent References
International ClassG05F 001/00AbstractThe present invention provides a method and circuit for controlling the flow of current through a load. In a preferred embodiment, an oscillator generates a pulse signal of constant frequency. A pulse width modulator adjusts the duty cycle of the pulse signal in response to a dimming level signal input indicative of the desired level of current flow through the load. A converter receives the pulse signal as an input and converts it into an AC signal, the frequency of which follows the frequency of the pulse signal and the symmetry of which varies with the duty cycle of the pulse signal. The load is connected into a resonant circuit tuned such that a change in the symmetry of the AC signal changes the level of current flowing through the load.Other References
Field of SearchAutomatic regulationRegulator responsive to plural conditions PERIODIC SWITCH IN THE SUPPLY CIRCUIT Periodic switch in the primary circuit of the supply transformer Impedance or current regulator in the supply circuit Plural periodic switches or multiple contact periodic switch Inductance in the condenser circuit Transformer in the condenser load device circuit PULSATING OR A.C. SUPPLY In inverter systems By pulse modulation technique (e.g., PWM, PPM, etc.) For inverter With transistor control means in the line circuit For bridge-type inverter Double ended (i.e., push-pull) type Separately driven Double-ended (i.e., push-pull), separately-driven type With automatic control of the magnitude of output voltage or current Utilizing pulse-width modulation | |
