Discharge lamp lighting circuit
First Claim
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1. A discharge lamp lighting circuit comprising:
- a DC power source circuit to output a bipolar voltage of positive polarity and negative polarity in reference to the ground potential;
a DC-AC conversion circuit for converting the DC voltage into an AC voltage and supplying the AC voltage to discharge lamps;
start circuits provided respectively for each discharge lamp to generate a high voltage signal for each discharge lamp; and
a common voltage supply circuit to supply a voltage to each start circuit.
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Abstract
A discharge lamp lighting circuit is provided with a DC power source circuit, a DC-AC conversion circuit, and start circuits. A primary circuit of a transformer in each start circuit has a capacitor and a switch element. When the voltage across the capacitor exceeds a threshold value, or when the switch element has electrical continuity, a high voltage is supplied separately to the discharge lamps from the primary coil through the secondary coil. A common voltage supply circuit supplies the voltage to the primary circuit of each start circuit from the DC power source circuit or the DC-AC conversion circuit.
7 Citations
9 Claims
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1. A discharge lamp lighting circuit comprising:
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a DC power source circuit to output a bipolar voltage of positive polarity and negative polarity in reference to the ground potential;
a DC-AC conversion circuit for converting the DC voltage into an AC voltage and supplying the AC voltage to discharge lamps;
start circuits provided respectively for each discharge lamp to generate a high voltage signal for each discharge lamp; and
a common voltage supply circuit to supply a voltage to each start circuit. - View Dependent Claims (2, 3, 4, 5, 6)
a plurality of switching elements in the DC-AC conversion circuit to switch the polarity of the voltage from the DC power source circuit and send the switched voltage to each discharge lamp; and
a drive circuit to control the switching of the switch elements.
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3. The discharge lamp lighting circuit according to claim 1, further comprising:
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a transformer in each start circuit including a magnetic substance and a primary coil and a secondary coil; and
a primary circuit of the transformer comprising a serial circuit of a capacitor and a switching element, the serial circuit being connected in parallel to the primary coil of the transformer.
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4. The discharge lamp lighting circuit according to claim 3, wherein when the voltage across the capacitor exceeds a threshold value according to the property of the capacitor or when the switching element achieves electrical continuity, the high voltage signal is applied to each discharge lamp from the primary coil through the secondary coil.
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5. The discharge lamp lighting circuit according to claim 3, wherein the common voltage supply circuit supplies a voltage from the DC power source circuit or the DC-AC conversion circuit to the primary circuit to charge the capacitor of the primary circuit of each start circuit.
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6. The discharge lamp lighting circuit according to claim 1, wherein when the high voltage signal is generated by the start circuit before lighting, the polarity of the voltage from the DC-AC conversion circuit for the discharge lamp to be turned on is regulated to be the reverse of the polarity of the voltage from the DC-AC conversion circuit for the discharge lamp which is not to be turned on yet.
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7. A discharge lamp lighting circuit comprising:
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discharge lamps;
a DC power source circuit to output a bipolar voltage of positive polarity and negative polarity in reference to the ground potential;
a DC-AC conversion circuit to convert the DC voltage into an AC voltage, which is supplied to the discharge lamps;
a plurality of switching elements in the DC-AC conversion circuit to switch the polarity of the voltage from the DC power source circuit and send the switched voltage to each discharge lamp;
a drive circuit to control the switching of the switch elements;
start circuits provided respectively for the discharge lamps to generate a high voltage signal for each discharge lamp; and
a common voltage supply circuit to supply a voltage to each start circuit;
a transformer in each start circuit including a magnetic substance and a primary coil and a secondary coil; and
a primary circuit of the transformer comprising a serial circuit of a capacitor and a switching element, the serial circuit being connected in parallel to the primary coil of the transformer, wherein the common voltage supply circuit supplies a voltage from the DC power source circuit or the DC-AC conversion circuit to the primary circuit to charge the capacitor of the primary circuit of each start circuit. - View Dependent Claims (8, 9)
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Specification