Discharge lamp lighting circuit with protection circuit
First Claim
1. A discharge lamp lighting circuit comprising:
- a lighting circuit which receives power from a power source and lights a discharge lamp;
a control circuit which detects an occurrence of a failure in a discharge lamp or the lighting circuit, the control circuit stops the power supplied to the discharge lamp or operation of the lighting circuit, and lights another light source as a substitute light source for the discharge light, or notifies the occurrence of the failure;
at least two switching means, one being connected to said lighting circuit for receiving power from the power source, while the other being connected to said control circuit for receiving another power from the power source, the respective switches being switched on substantially in synchronization with one another;
wherein said control circuit is prohibited from stopping the power supply to the discharge lamp, or stopping the operation of the lighting circuit, or lighting the substitute light source, or notifying the occurrence of a failure until a predefined time period is elapsed from the time said switch means are switched on to cause the lighting circuit to start operating.
1 Assignment
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Accused Products
Abstract
In a discharge lamp lighting circuit 1, a control circuit 7 detects a failure in a discharge lamp 8 or the lighting circuit to stop supplying the power to the discharge lamp 8 or stop the operation of the lighting circuit, or lights another light source as a substitute light source for the discharge lamp and notifies the occurrence of a failure when the discharge lamp 8 can no longer be lit. A delay time generator circuit 31 is provided for a failure detection/determination circuit 22 such that the foregoing functions are prohibited until a predefined time period is elapsed after the time switch means SW1, SW2 are substantially simultaneously switched on to cause the lighting circuit to start operating.
30 Citations
5 Claims
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1. A discharge lamp lighting circuit comprising:
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a lighting circuit which receives power from a power source and lights a discharge lamp;
a control circuit which detects an occurrence of a failure in a discharge lamp or the lighting circuit, the control circuit stops the power supplied to the discharge lamp or operation of the lighting circuit, and lights another light source as a substitute light source for the discharge light, or notifies the occurrence of the failure;
at least two switching means, one being connected to said lighting circuit for receiving power from the power source, while the other being connected to said control circuit for receiving another power from the power source, the respective switches being switched on substantially in synchronization with one another;
wherein said control circuit is prohibited from stopping the power supply to the discharge lamp, or stopping the operation of the lighting circuit, or lighting the substitute light source, or notifying the occurrence of a failure until a predefined time period is elapsed from the time said switch means are switched on to cause the lighting circuit to start operating. - View Dependent Claims (2, 3, 4, 5)
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Specification