Patent application number | Description | Published |
20100157257 | HIGH PRESSURE DISCHARGE LAMP BALLAST, HIGH PRESSURE DISCHARGEP LAMP DRIVING METHOD, AND PROJECTOR - A high pressure discharge lamp ballast includes an AC power supply means for supplying a square wave alternating current to a high pressure discharge lamp having a bulb in which first and second electrodes are disposed so as to face each other. In the high pressure discharge lamp ballast, one modulation period (T | 06-24-2010 |
20110025222 | HIGH PRESSURE DISCHARGE LAMP BALLAST AND LIGHT SOURCE APPARATUS - In a frequency control for a high pressure discharge lamp ballast, short-term increase and decrease of a lamp voltage are suppressed. The high pressure discharge lamp ballast drives a high pressure discharge lamp with a synthesized-waveform alternating current made of multiple frequency components, the high pressure discharge lamp having a pair of electrodes disposed to face each other. The ballast includes: a control means for controlling a component contained ratio of the multiple frequency components per unit time; an output means for applying a synthesized-waveform current in accordance with the component contained ratio to the high pressure discharge lamp; and detection means for detecting a lamp parameter of the high pressure discharge lamp. The control circuit is configured to shift the component contained ratio to a first component contained ratio when the lamp parameter is in a first state, and shift the component contained ratio to a second component contained ratio when the lamp parameter is in a second state. The control circuit is configured to change the component contained ratio stepwise when the component contained ratio is shifted from the first component contained ratio to the second component contained ratio, or when the component contained ratio is shifted from the second component contained ratio to the first component contained ratio. | 02-03-2011 |
20110025223 | HIGH PRESSURE DISCHARGE LAMP BALLAST AND LIGHT SOURCE APPARATUS - Even when usable driving frequencies are limited, a lamp voltage is appropriately controlled. A high pressure discharge lamp ballast performs driving with a synthesized current waveform comprising a combination of first and second sets of current waveforms. The ballast includes: a control means for controlling content rates of each of the sets per unit time; a detection means for detecting a rotation synchronization signal for a color wheel; an output means for applying a synthesized current waveform in accordance with the synchronization signal and the content rates to a high pressure discharge lamp; and a detection means for detecting a lamp voltage. The sets are each in a waveform inverted so as to correspond to at least one of a rotational speed and segment positions of color wheel. A period of each of the first and second sets has a length equivalent to one rotation of the color wheel. The number of inversions of the second set is larger than the number of inversions of the first set. The ballast is configured in that the content rate of the second set is set to R | 02-03-2011 |
20130038843 | HIGH PRESSURE DISCHARGE LAMP BALLAST AND A METHOD FOR DRIVING A HIGH PRESSURE DISCHARGE LAMP BALLAST - The high pressure discharge lamp ballast of the present invention includes: power supply means for supplying an AC current to a lamp; and control means for cyclically changing a current value of the AC current to be supplied and a time interval between polarity inversions. The AC current has a cycle of a time period TL and a time period TS, and the power supply means is controlled by the control means to apply a half cycle of a first low frequency current and, immediately after that, apply one cycle of a high frequency current in the time period TL, the high frequency current in only the second half of the cycle or the entire cycle having a peak current value that is higher than a current value of the first low frequency current, and to repeat cycles of only a second low frequency current in the time period | 02-14-2013 |