Mitsubishi Electric Corporation

Hayato Takeuchi

Kuniko Kojima

Yuzo Nakano

Takao Endo

Takaharu Ishibashi

Takushi Jimichi

Tomohiro Sasagawa

Kenichi Fukuno

Akihiro Yamada

Norihiro Watanabe

Takato Toi

An object is to obtain a power conversion device that can prevent ripple from increasing owing to change in switching frequency. A power conversion device includes: semiconductor switching elements connected between a DC voltage source and an output side, and connected in series to each other; a reactor; a control unit which controls a switching frequency of each semiconductor switching element; and a voltage detector, a voltage detector, and a current detector which respectively detect a voltage value of an input voltage, a voltage value of an output voltage, and a current value of an inductor current. Changing of the switching frequency and detection of the voltage value of the input voltage, the voltage value of the output voltage, and the current value of the inductor current are each performed at a timing that allows synchronization with a carrier.

Power conversion device with loss minimization and synchronized detection and switching frequency changing

The present disclosure suppresses increase in device cost in a DC power distribution system that can disconnect a distribution line on which a short-circuit failure has occurred, from an output path. This DC power distribution system includes: a plurality of power conversion devices; one DC busbar; a plurality of distribution lines; a plurality of first current interruption portions respectively connected to input sides of the power conversion devices; a plurality of second current interruption portions connected between the power conversion devices and the DC busbar; and a plurality of third current interruption portions respectively provided on the distribution lines. Interruption current values of the third current interruption portions are set to smaller values than a maximum allowable current value of the power conversion device in which short-circuit current will reach the maximum allowable current value in a shortest time.

DC power distribution system

A DC power distribution system includes: a transformer; a rectification device; a DC bus through which DC power flows; a plurality of DC branch lines branching off from the DC bus; an AC interrupting portion connected to an input side of the transformer; a first DC interrupting portion connected between the rectification device and the DC bus; and a plurality of second DC interrupting portions respectively provided to the plurality of DC branch lines. An interrupting-operation time for each second DC interrupting portion is set to be shorter than interrupting-operation times for the AC interrupting portion and the first DC interrupting portion. An inductance value of a short-circuit impedance of the transformer is set to a value at which short-circuit current can be limited to take a value not larger than a maximum current value permitted for the rectification device.

A projection display device has an illumination optical system that includes a light-intensity equalization element, a first optical system, and an aperture regulation member. The aperture regulation member is disposed at a position that is not optically conjugate with the screen, and the aperture regulation member has at least one of the following, using measured or calculated relative illuminances at each of multiple segments of the image formation region or screen: an aperture expansion part provided at a position corresponding to a segment with a low relative illuminance, the aperture expansion part being a cutout that narrows the light-blocking section and widens the aperture section; an aperture contraction part provided at a position corresponding to a segment with a high relative illuminance, the aperture contraction part being a protrusion that widens the light-blocking section and narrows the aperture section.

Projection display device

A projection-type display apparatus that projects an image on a screen and performs image display includes at least one laser source that emits a coherent light beam, an illuminating optics that propagates the light beam emitted from the laser source into a predetermined optical path to guide the light beam to the screen, a reflective optical modulator that forms the image to be displayed on the screen on an illuminated surface illuminated by the light beam guided by the illuminating optics, and a projection optics that magnifies and projects the image formed on the illuminated surface of the reflective optical modulator on the screen. The illuminating optics includes a diffusion device, which diffuses the propagated light beam, and is arranged on a light propagation path near a conjugated position with the reflective optical modulator.

Projection-type display apparatus

An image formed on a reflecting optical modulator is magnified by a projection optical system and projected on a backside of a transmission-type screen. The projection optical system is constituted so that a product of an F-number and a projection magnification of the projection optical system is less than 400.

Projection-type display apparatus with a projection optical system configured to reduce speckle

A transmission-type screen includes an entering-side Fresnel lens that inflects image light from a light emitter toward a display side using a prism formed on a rear-surface side, which is a light-entering-surface side of the image light; a first light diffusing unit that is provided on the display side with respect to the entering-side Fresnel lens and diffuses the image light from the entering-side Fresnel lens; a second light diffusing unit provided on the display side with respect to the first light diffusing unit, diffuses the image light from the first light diffusing unit, causes the diffused image light to exit toward the display side, and configured to change a relative position thereof to the first light diffusing unit; and a second substrate that holds the second light diffusing unit while being provided on the display side with respect to the second light diffusing unit.

Transmission-type screen, projection-type display device, and image displaying method

A Fresnel lens screenis comprised of a light entering surface partial total reflection type Fresnel lens, a first light diffusing partdisposed behind the Fresnel lens, and a first base. An image display elementdisposed behind the Fresnel lens screenhas a lens element, a second base, and a third base. Second light diffusing partsare disposed behind the second base. Each of the second light diffusing partsincludes two types of particulates having different particle sizes which are distributed therein.

Transparent screen, projection display device, and image display method

A transparent screen is constructed in such a way that a plurality of Fresnel prismseach of which is smaller than a plurality of Fresnel prismsand has a shape approximately similar to that of each of the plurality of Fresnel prismsare arranged in a sawtooth shape on a non-light incidence surface portion of a Fresnel lenson a light incidence side to which any image light PB applied from a projectoris not applied directly because blocked by a Fresnel prismplaced frontwardly.

Transparent screen, projection display device, and method of receiving control signal light

An illuminating optical system propagates a coherent light flux from at least one light source into a predetermined optical path to guide the light flux to a screen. A light bulb forms an image to be displayed on the screen on an illumination area illuminated with the light flux that is guided by the illuminating optical system. A projecting optical unit projects the image that is formed on the illumination area onto the screen in a magnifying manner. The illuminating optical system includes a diffusing unit that diffuses the light flux from the light source near a focusing position of the illuminating optical system.

Project display apparatus having diffusion element for reducing speckle

The Fresnel lens sheet according to the present invention has a plurality of prismatic Fresnel lens elements including a Fresnel facet, a riser facet, and a top facet crossing the facet and the riser facet on an entrance surface. An angle of the top facet of each Fresnel lens element constituting the lens relative to the an exit surface, &#x3b4;, is determined so that an exit angle of the light that has entered each of the top facets and exits from the exit surface, &#x3b2;, is greater than 35 degrees.

Growing community of inventors

Tokyo, Japan

Hayato Takeuchi