Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Hiroji Morimoto

Syunsuke Ono

Minoru Ozasa

Masahiro Yamamoto

Kazuo Takeda

A calculation processing sub-unit controls a frequency control sub-unit and a DC-AC inverter circuit to repeat a first period and a second period. The first period continues for at least two cycles, each cycle including a first sub-period during which the current is maintained in one polarity and a second sub-period during which the current is maintained in an opposite polarity. The second sub-period is shorter than and subsequent to the first sub-period. The second period, during which the current is maintained in a constant polarity, is as long as or longer than the first sub-period. The calculation processing sub-unit controls a PWM control sub-unit and a voltage step-down circuit to maintain an absolute value of the current at a first current value during at least part of the first period, and at a second current value, greater than the first current value, during the second period.

High pressure discharge lamp lighting device, projector provided with the same, and high pressure discharge lamp lighting method

A high-pressure discharge lamp lighting device that suppresses deterioration and the expansion of inter-electrode distance in a pair of electrodes within a high-pressure discharge lamp, more effectively than conventional technology. The frequency of the AC current supplied to a high-pressure discharge lamp alternates between a first frequency and a second, higher frequency, while the magnitude of the AC current alternates between a first value and a second, higher value. The suppressing effect is realized by repeatedly alternating the frequency and repeatedly alternating between a first period at the first frequency and a second period at the second frequency, with the second, higher-magnitude current being used in the latter and the first current being used in the former.

High-pressure discharge lamp light-up device, high-pressure discharge lamp apparatus using same, projector using high-pressure discharge lamp apparatus, and light-up method for high-pressure discharge lamp

The frequency of the alternating current to be supplied to the high-pressure discharge lamp is switched among a first frequency, a second frequency greater than the first frequency, and a third frequency smaller than or equal to the first frequency. In the switching, a period A, in which the alternating current of the third frequency is supplied, occurs at the beginning of each of the predetermined time intervals. A remainder of each of the predetermined time intervals includes a period B, in which the alternating current of the first frequency is supplied, and a period C, in which the alternating current of the second frequency is supplied, the periods B and C being alternately repeated, so as to control the period A to be longer than the period B and to have a length corresponding to a predetermined number of cycles, ranging from 5.5 to 50 cycles inclusive.

High-pressure discharge lamp lighting device, high pressure discharge lamp apparatus using this, projector using the high-pressure discharge lamp apparatus, and high-pressure discharge lamp lighting method

A metal vapor discharge lamp and a lighting fixture are downsized without causing breakage of an outer tube because of optimization of a positional relation among the outer tube (), an inner tube (), and an arc tube (). The metal vapor discharge lamp has the arc tube, the inner tube housing the arc tube, and the outer tube housing the inner tube. The positional relation satisfies the relation of 2&#xd7;A+B&#x2267;1.06. In a cross section of the lamp (the cross section of the arc tube is unshown for convenience), A (mm) represents the shortest distance between the arc tube and the inner tube along a line in a radial direction of the inner tube, and B (mm) represents a distance between the inner tube and the outer tube on a line segment C that is extension of the line.

Growing community of inventors

Nara, Japan

Hiroji Morimoto