Abstract: An elevator control device includes: a convertor which rectifies a.c. power and converts the a.c. power into d.c. power; an inverter which converts the d.c. power into a.c. power having a variable voltage and a variable frequency; an electric motor which is driven by the a. c. power having a variable voltage and a variable frequency to operate an elevator; a power storing unit which is charged with electric power; a required-power arithmetically operating circuit which calculates power required by the elevator, which is an electric power required for the operation of the elevator or an electric power caused by the operation of the elevator; and a charging/discharging control circuit which controls charging and discharging of the power storing unit based on the power required by the elevator.
Type:
Grant
Filed:
February 12, 2001
Date of Patent:
August 20, 2002
Assignees:
Mitsubishi Denki Kabuskiki Kaisha, The Tokyo Electirc Power Company, Ince
Abstract: A projection display device comprises: a diaphragm for the illuminating system disposed in the vicinity of a focal point of the light collected by the concave mirror; a collimation lens for rendering parallel the light passing through the aperture of the first diaphragm; a scattering-type liquid crystal light valve for forming forming image on its displaying surface; a field lens for converging the light rendered parallel by the collimation lens; a projection lens having an entrance pupil disposed in the vicinity of a focal point of the light converged by the field lens; and a second diaphragm having an aperture and provided in the projection lens. An aperture varying section of the first diaphragm varies the aperture diameter of the diaphragm of the illuminating system, and the other aperture varying section varies the aperture diameter of the diaphragm of the projection lens, thereby varying the diameter of an entrance pupil.