Mitsubishi Denki Kabushiki Kaisha

Hitachi-johnson Controls Air Conditioning, Inc.

Juki Corporation

Yuuji Yamamoto

Masayuki Tsuji

Yasuo Notohara

Shinji Takeuchi

Hiroshi Onishi

Takuji Kurashita

Dongsheng Li

Hitoshi Hasegawa

Naohiro Fujimura

Tamaki Yokote

An inverter, motor drive device and freezing device, with which it is possible to effectively suppress current beats in the event of over-modulation without requiring additional circuits. This motor driving device includes: a rectifier circuit that converts the AC voltage from an AC power supply into a DC voltage; a smoothing capacitor that smoothes the DC voltage output from the rectifier circuit; an inverter circuit that converts the DC voltage output from the smoothing capacitor into an AC voltage; and a controller that reduces the current beat component by estimating, using a phase locked loop process, the frequency, phase and amplitude of the current beat component in the output current of the inverter circuit, and corrects the voltage command to the inverter circuit on the basis of the estimated frequency, phase and amplitude.

Inverter and motor drive device, freezing device

A video contrast enhancer enhances luminance contrast by dividing each video frame or field into blocks, calculating a mean luminance level for each block, selecting mapping functions on the basis of these mean luminance levels over a series of frames or fields, and mapping the video luminance levels according to the selected mapping functions. Color-saturation contrast is enhanced by modifying the amplitude of the modulated chrominance signal by the histogram equalization method, preferably by making a single linear modification in each period of the chrominance signal, so that color phase is not affected. For video signals with non-picture bands, these enhancements are preferably restricted to the picture area. If a black offset is present, it is preferably removed.

Video contrast enhancer

Growing community of inventors

Tokyo, Japan

Yuuji Yamamoto