Ushio Denki Kabushiki Kaisha

Isao Miyake

Masashi Okamoto

Takanori Samejima

A polarity-reversal control circuit gives a polarity-reversal order so that the polarity of an inverter is inverted each time the polarity-reversal timing notified by a signal is recognized. The number of times of consecutive appearances of a normal polarity-reversal interval period, in which an interval of adjoining polarity-reversal timings is equal to or less than an upper limit of a polarity-reversal interval desirable for a discharge lamp, is counted, and if the unusual polarity-reversal interval period, in which an interval of the adjoining polarity-reversal timing is longer than the upper limit of a polarity-reversal interval, appears, Npm is memorized as the maximum of the number of times of consecutive appearances and after that, when the polarity-reversals signal in which the number of times of consecutive appearances becomes equal to Npm is received, it is regarded as a start of an unusual polarity-reversal interval period, and additional polarity-reversal order is given.

Discharge lamp lighting apparatus and projector

The present discharge lamp lighting device is capable of rapidly breaking or restoring a lamp current or of rapidly reducing or restoring the lamp current. A discharge lamp lighting device, comprises a power supply circuit which supplies power to a discharge lamp, a current breaking switch circuit which selectively interrupts a current flowing through the discharge lamp, a lamp condition detector which detects a condition of the discharge lamp, a target signal generating circuit which generates a target signal for lighting the discharge lamp in a predetermined condition, based on an output from the lamp condition detector, and a target signal holding circuit which selectively holds the target signal, wherein when the current is interrupted by the current breaking switch circuit, the target signal holding circuit holds the target signal.

Growing community of inventors

Hyogo, Japan

Isao Miyake