Discharge lamp ignition device, equipment and image forming apparatus

A discharge lamp ignition device comprising:

• a discharge lamp including a discharge container filled with a discharge medium mainly includes a rare gas and a pair of electrodes at least one of which is disposed on the outer surface of the discharge container;
• a feeding harness line having its one end connected to the discharge lamp, the harness line including parallel conductors the length of which is 200 mm or more;
• and
• an ignition circuit connected to the other end of the feeding harness line to ignite the discharge lamp,
• the ignition circuit including:
• high-frequency voltage generator, comprising a switch configured to generate a high-frequency voltage through high-frequency switching and an output transformer which outputs a high-frequency voltage, configured to ignite the discharge lamp by applying the high-frequency output voltage of the output transformer between the paired electrodes of the discharge lamp;
• no-load detector configured to detect a no-load state based on a current which flows in the secondary circuit of the output transformer;
• high-frequency oscillating current bypass coupled to the no-load detector configured to bypass a high-frequency oscillating current which flows in the no-load detector at no-load time mainly due to the stray capacitance of the feeding harness line to thereby reduce the high-frequency oscillating current to flow in the no-load detector;
• and
• controller, when the no-load detector detects a no-load state, configured to control the high-frequency voltage generator to protect the ignition circuit.

A discharge lamp ignition device comprising:

• a discharge lamp including a discharge container filled with a discharge medium mainly including a rare gas and a pair of electrodes at least one of which is disposed on the outer surface of the discharge container, the interelectrode internal stray capacitance within the discharge container being CIE and the interelectrode creepage stray capacitance across the surface of the discharge container being CSF;
• a feeding harness line having its one end connected to the discharge lamp, the harness line including parallel conductors and having a stray capacitance of CHN associated with the parallel conductors;
• and
• an ignition circuit connected to the other end of the feeding harness line to ignite the discharge lamp,
• the ignition circuit including:
• high-frequency voltage generator, comprising a switch configured to generate a high-frequency voltage through high-frequency switching and an output transformer which outputs a high-frequency voltage, for igniting the discharge lamp by applying the high-frequency output voltage of the output transformer between the paired electrodes of the discharge lamp;
• no-load detector configured to detect a no-load state based on a current which flows in the secondary circuit of the output transformer;
• high-frequency oscillating current bypass coupled to the no-load detector configured to bypass a high-frequency oscillating current which flows in the no-load detector at no-load time mainly due to the stray capacitance of the feeding harness line to thereby reduce the high-frequency oscillating current to flow in the no-load detector;
• and
• controller, when the no-load detector detects a no-load state, configured to control the high-frequency voltage generator to protect the ignition circuit,
• the capacitances CIE, CSF and CHN being set to satisfy CIE>CHN>CSF.