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US 7,479,742 B2Granted
Discharge lamp lighting circuit
AssigneeKoito Manufacturing Co., Ltd.
InventorsKotaro Matsui, Tomoyuki Ichikawa, Soichi Yagi
Life of this patent
Estimating the term…
Abstract
A discharge lamp lighting circuit 1 includes a direct current-alternating current converting circuit 3, a starting circuit 4, controlling means 15 for controlling power, switching elements 5H, 5L driven by the controlling means 15 and a series LC resonance circuit (7p, 8, 9). A frequency modulating circuit is provided for restraining acoustic resonance by modulating a frequency of driving the switching element. When a basic frequency related to the drive frequency is equal to or higher than 1 MHz, a modulation width is set to be equal to or higher than 20 kHz.
Claims11
A discharge lamp lighting circuit comprising:
- a direct current-alternating current converting circuit for receiving a direct current input voltage and converting the direct current input voltage to an alternating current voltage,
- a starting circuit for supplying a starting signal to a discharge lamp, and
- controlling means for controlling a power provided by the direct current-alternating current converting circuit;
- wherein the direct current-alternating current converting circuit comprises switching elements driven by the controlling means and a series resonating circuit including a capacitor and at least one of an inductance element or a transformer, the direct current-alternating current converting circuit further including:
- a frequency modulating circuit for restraining an acoustic resonance by modulating a frequency of driving the switching elements;
- and
- a limiter circuit for preventing the frequency of driving the switching elements from exceeding an upper limit frequency capable of maintaining a state of lighting the discharge lamp (Fmax).
4 more elements
A discharge lamp lighting circuit comprising:
- a direct current-alternating current converting circuit for receiving a direct current input voltage and converting the direct current input voltage to an alternating current voltage,
- a starting circuit for supplying a starting signal to a discharge lamp, and
- controlling means for controlling a power provided by the direct current-alternating current converting circuit;
- wherein the direct current-alternating current converting circuit comprises switching elements driven by the controlling means and a series resonating circuit including a capacitor and at least one of an inductance element or a transformer, the direct current-alternating current converting circuit further including:
- a frequency modulating circuit for restraining an acoustic resonance by modulating a frequency of driving the switching elements;
- wherein the controlling means includes a voltage-frequency converting portion for outputting a signal of a frequency changed in accordance with an input voltage;
- and the controlling means is configured so that the output signal of the voltage-frequency converting portion is subjected to a frequency modulation by an output signal of the frequency modulating circuit, and a drive signal generated based on the frequency-modulated output signal of the voltage-frequency converting portion is supplied to the switching elements.
4 more elements
A discharge lamp lighting circuit comprising:
- a direct current-alternating current converting circuit for receiving a direct current input voltage and converting the direct current input voltage to an alternating current voltage,
- a starting circuit for supplying a starting signal to a discharge lamp, and
- controlling means for controlling a power provided by the direct current-alternating current converting circuit;
- wherein the direct current-alternating current converting circuit comprises switching elements driven by the controlling means and a series resonating circuit including a capacitor and at least one of an inductance element or a transformer, the direct current-alternating current converting circuit further including:
- a frequency modulating circuit for restraining an acoustic resonance by modulating a frequency of driving the switching elements;
- wherein the controlling means includes a voltage-frequency converting portion for outputting a signal of a frequency changed in accordance with an input voltage;
- and the controlling means is configured so that the input voltage modulated by an output signal of the frequency modulating circuit is supplied to the voltage-frequency converting portion, and a drive signal generated based on the output signal of the voltage-frequency converting portion is supplied to the switching elements.
4 more elements
Dependencies are inferred from the claim text.