Starting circuit for a high intensity discharge lamp
First Claim
1. A circuit for coupling energy from an AC source to a high intensity discharge lamp having electrodes, comprising:
- an inductor in series with said source and lamp;
a control circuit coupled between said inductor and lamp at a common point;
said control circuit comprisinga diode connected at a first terminal to said common point;
a load resistor and first transistor circuit connected in series between a second terminal of said diode and ground, wherein said first transistor circuit is biased for ON operation at a first signal voltage level of said source to provide a current path through said load resistor for charging said inductor; and
a second transistor circuit connected between the second terminal of said diode and ground and operatively coupled to said first transistor circuit, wherein said second transistor circuit is biased for ON operation at a second signal voltage level to force said first transistor circuit into an OFF operation.
1 Assignment
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Accused Products
Abstract
A starting circuit is used in combination with a high intensity discharge lamp having electrodes. An inductor is in series with the electrodes of the lamp, and a first switching transistor is arranged in series with a diode and a load resistor. The first switching transistor, diode, and resistor are arranged in shunt with the electrodes of the lamp and in series with the inductor for charging the inductor when the first switching transistor is switched ON. The energy stored in the inductor is discharged as a voltage pulse across the lamp when the first switching transistor is switched OFF. A first bias circuit turns the first switching transistor ON at a first voltage level from an AC power source. A second switching transistor turns the first transistor OFF at a second voltage level. A second bias circuit turns the second switching transistor ON at the second voltage.
7 Citations
11 Claims
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1. A circuit for coupling energy from an AC source to a high intensity discharge lamp having electrodes, comprising:
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an inductor in series with said source and lamp; a control circuit coupled between said inductor and lamp at a common point; said control circuit comprising a diode connected at a first terminal to said common point; a load resistor and first transistor circuit connected in series between a second terminal of said diode and ground, wherein said first transistor circuit is biased for ON operation at a first signal voltage level of said source to provide a current path through said load resistor for charging said inductor; and a second transistor circuit connected between the second terminal of said diode and ground and operatively coupled to said first transistor circuit, wherein said second transistor circuit is biased for ON operation at a second signal voltage level to force said first transistor circuit into an OFF operation. - View Dependent Claims (2, 3, 4, 5, 7, 8, 9, 10)
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6. A starting circuit in combination with a high intensity discharge lamp having electrodes forming a capacitor, comprising:
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an inductor in series with the electrodes of said lamp; a diode; a load resistor; a first switching transistor arranged in series with said load resistor and said diode, wherein said first switching transistor, said diode and said load resistor are arranged in shunt with the electrodes of said lamp and in series with said inductor for charging said inductor with inductive energy when said first switching transistor is ON, and for discharging the energy stored in said inductor as a voltage pulse across said lamp when said first switching transistor is OFF; a first bias circuit adapted to turn said first switching transistor ON at a first voltage; a second switching transistor adapted to turn said first transistor OFF at a second voltage; and a second bias circuit arranged to turn said second switching transistor ON at said second voltage.
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11. A circuit for coupling energy from an AC source to a high intensity discharge lamp having electrodes, comprising:
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an inductor in series with said source and lamp; a control circuit coupled between said inductor and lamp at a common point; said control circuit comprising a diode connected at a first terminal to said common point; a transistor having a first, second, and third terminal; a thermal switch operating in a normally-closed state, and coupled between the third terminal of said transistor and ground; a first resistor coupled between a second terminal of said diode and the first terminal of said transistor; a second resistor coupled between the first terminal of said transistor and ground; and a third resistor coupled between the second terminal of said diode and the second terminal of said transistor.
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Specification