Discharge lamp starter, method for controlling the same, and projector

A discharge lamp lighting apparatus comprising:

• a power control circuit that outputs a DC current;
• an AC conversion circuit to which the DC current is inputted, the AC conversion circuit repeatedly reversing a polarity of the DC current between a first polarity and a second polarity at predetermined timings to produce and output a discharge lamp driving AC current;
• and
• a controller configured to control the AC conversion circuit to perform an AC conversion control where the timings at which a polarity of the discharge lamp driving AC current is reversed are used to control a duty ratio of the discharge lamp driving AC current, the duty ratio being a proportion of a period of the first polarity to one cycle of the discharge lamp driving AC current, and the controller configured to control the power control circuit to perform a current control for controlling a magnitude of the DC current,
• wherein the controller performs the AC conversion control such that the duty ratio of the discharge lamp driving AC current is changed in accordance with a periodic pattern,
• the periodic pattern includes a plurality of segmented periods during each of which the duty ratio is maintained at a value for a plurality of cycles of the discharge lamp driving AC current, and the duty ratio of at least two of the segmented periods differ from each other, and
• the controller performs the current control by externally receiving a power control signal and setting an average of the DC current in a section that corresponds to the one cycle of the discharge lamp driving AC current to a current magnitude that corresponds to the power control signal, and performs the AC conversion control such that a difference between at least one of a maximum and minimum values of the duty ratio and a reference duty ratio is controlled in relation to the average value of the DC current.

A discharge lamp lighting apparatus comprising:

• a power control circuit that outputs a DC current;
• an AC conversion circuit to which the DC current is inputted, the AC conversion circuit repeatedly reversing a polarity of the DC current between a first polarity and a second polarity at predetermined timings to produce and output a discharge lamp driving AC current;
• and
• a controller configured to control the AC conversion circuit to perform an AC conversion control for controlling the timings at which a polarity of the discharge lamp driving AC current is reversed and configured to control the power control circuit to perform a section current control for controlling a magnitude of the DC current,
• wherein the controller performs the section current control such that a difference in an absolute value of a current magnitude between a first polarity section and a second polarity section of the discharge lamp driving AC current is changed in accordance with a periodic pattern,
• the periodic pattern includes a plurality of segmented periods during each of which the difference in the absolute value is maintained at a same value for a plurality of cycles of the discharge lamp driving AC current, and differences in the absolute value in at least two of the segmented periods differ from each other, and
• the controller performs the section current control by externally receiving a power control signal and setting an average of the DC current in a section that corresponds to one cycle of the discharge lamp driving AC current to a current magnitude that corresponds to the power control signal, and controlling the difference in the absolute value in relation to the average value of the DC current.

A method for controlling a discharge lamp lighting apparatus including

• a power control circuit that outputs a DC current, and
• an AC conversion circuit to which the DC current is inputted, the AC conversion circuit reversing a polarity of the DC current at predetermined timings to produce and output a discharge lamp driving AC current,
• the method comprising:
• controlling the AC conversion circuit to perform an AC conversion control for controlling the timings at which a polarity of the discharge lamp driving AC current is reversed;
• controlling the power control circuit to perform a current control for controlling a magnitude of the DC current;
• and
• changing an accumulated energy supplied to each electrode of a discharge lamp in one cycle of the discharge lamp driving AC current in accordance with a periodic pattern,
• wherein the periodic pattern includes a plurality of segmented periods during each of which the accumulated energy is maintained at a same level for a plurality of cycles of the discharge lamp driving AC current, and a level of the accumulated energy in at least two of the segmented periods differ from each other, and wherein
• the changing in accordance with the periodic pattern includes performing the current control by externally receiving a power control signal and setting an average of the DC current in a section that corresponds to the one cycle of the discharge lamp driving AC current to a current magnitude that corresponds to the power control signal, and controlling a magnitude of the accumulated energy in relation to the average value of the DC current.