Koito Manufacturing Company, Ltd.

Atsuhiko Murata

Goichi Oda

Akihiro Matsumoto

Masaru Sasaki

Akiyoshi Ozaki

Soichi Yagi

Yuji Yoshimoto

Masaya Shidoh

Kazuyuki Miyake

A lighting circuit for a vehicular discharge lamp comprises a DC-to-AC converter, a lamp voltage detector, a lamp current detector, a voltage-current controller, and a power change reducing means. The DC-to-AC converter converts a DC voltage into an AC voltage and supplies it to the discharge lamp. The lamp voltage detector acquires a detection signal concerning a lamp voltage of the discharge lamp. The lamp current detector acquires a detection signal concerning a lamp current of the discharge lamp. The voltage-current controller produces a lamp current controller instruction signal generated with respect to the lamp voltage upon reception of the detection signal from the lamp voltage detector, and supplies a control signal to the DC-to-AC converter so as to minimize differences between the instruction signal and the detection signal from the lamp current detector, thereby controlling the output voltage of the DC-to-AC converter. This controller has at least a lighting acceleration area for producing the lamp-current control instruction signal to permit supply of greater power than rated power of the discharge lamp and a steady power control area for performing steady power control of the discharge lamp with the rated power, as a control area based on lamp voltage-lamp current characteristic. The power change reducing means suppresses a change in power supply to the discharge lamp with respect to the lamp voltage at a time of transition to the steady power control area from the lighting acceleration area, thereby shortening the time required for flux of light from the discharge lamp to become stable.

Lighting circuit for vehicular discharge lamp

A lighting circuit for a metallic halide lamp for vehicular headlight applications is disclosed. Included are a pair of input terminals between which a battery is connected for feeding the lamp via a normally open relay switch which is closed upon energization of an associated relay coil. The relay coil is connected in series with an operator actuated lamp switch and a protection switch, so that both lamp switch and protection switch must be closed to energize the relay coil and hence to close the relay switch. The protection switch is automatically opened to deenergize the relay coil when the battery develops overvoltage or when the lamp will not glow upon closure of the lamp switch. In an alternate embodiment, the protection switch is also opened in response to the development of overcurrent or overvoltage by a d.c. voltage booster circuit included in the lighting circuit.

Lamp lighting circuit with an overload protection capability

A color liquid crystal display unit having improved resolution with good color mixing and little directivity. The display unit includes upper and lower light-transmissible substrates disposed in opposition to one another, scanning and signal electrodes formed on opposed surfaces of the substrates, color filters formed at a predetermined repetition interval on the signal electrodes, and a liquid crystal enclosed between the upper and lower substrates. At least one of the signal electrodes is divided into plural portions, and at least a portion of another signal electrode is interleaved therewith.

Color liquid-crystal display unit with electrodes interleaved in

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Shimizu, Japan

Atsuhiko Murata