Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Toshiyuki Noguchi

Yasuhiro Kakimoto

Mitsuru Kotaka

Shigekazu Yamagishi

Satoshi Hamada

Tetsuro Shiota

Yoshinobu Nakajima

Kazuo Mukai

Yoshinari Matsumoto

Kenji Kunitake

A housing () that accommodates a light source (), a display device (), etc. has an intake aperture () and an exhaust aperture (). A blowing unit () sucks air in through the intake aperture and expels air out through the exhaust aperture. A filter unit () is disposed so that a filter () faces the intake aperture in a predetermined area between a rolling shaft () and a take-up shaft (). A part of the filter facing the intake aperture is renewed by taking-up the filter from the rolling shaft onto the take-up shaft. A control unit () performs control so as to renew the filter for a range that is smaller than an opening area of the intake aperture, when a predetermined renewal condition is determined to be satisfied, based on the output of a detection unit () that detects a specific factor value relating to contamination of the filter, such as a cumulative display time, a temperature, an air pressure, etc. This reduces a noise occurring during the driving of a fan or a change in the rotational speed of the fan, which are associated with automatic filter renewal.

Projector, and its filter renewal control method

An operating device control section () controls an output current of a DC-DC converter (), and also controls a commutation frequency of a commutator () that converts a direct current output from the DC-DC converter into an alternating current. The operating device control section operates a discharge lamp, at the start of lamp operation, with a predetermined voltage value lower than a rated voltage and a first target current value higher than a rated current, then, at an end of a predetermined high frequency start period (T) elapsed from the start of lamp operation, controls the commutator to switch from a commutation frequency higher than that during a steady lamp operation to a commutation frequency during the steady lamp operation, and then, after a voltage applied to the discharge lamp increases and reaches a voltage not lower than a predetermined threshold voltage (Vth) which is not higher than the rated voltage, controls the DC-DC converter to switch from the first target current value to a second target current value which is not higher than the rated current to operate the discharge lamp. A temperature of a lamp electrode can be increased quickly and sufficiently to reduce a time required to increase the lamp illuminance, thereby reducing a time required to cause video to be viewable.

Ballast for high-pressure discharge lamp and method of operating the same

An image display device which has a display element that optically modulates an incident light for displaying an image. A lamp is a light source of the incident light to the display element. A lamp driver drives the lamp. A lamp power level calculator calculates a driving power level of the lamp corresponding to a level of an input video signal. A lamp temperature controller controls a lamp temperature depending on changes in the input signal from the lamp power level calculator so as to change the lamp temperature within a predetermined range in response to fluctuations of the input video signal. This image display device can further include a projection lens for projecting and displaying images formed in the display element on a screen.

Image display

A discharge-lamp lighting device is provided which decreases arc jumps, suppresses the fluctuation in brightness of the lamp, and prolongs a life of the lamp, by positively accelerating growth of spots even when an inexpensive, small and highly efficient lamp is used. A discharge-lamp controlling portion ( ) sets frequencies of drive-controlling signals (A and B) for drive-controlling a commutator ( ) within a predetermined frequency range so that spots formed by arc discharge on electrodes composing a high-pressure discharge lamp grow through a cycle of oxidation-reduction of a metal composing the electrodes, and superimposes a triangular wave signal generated on the basis of the drive-controlling signals onto a current-controlling signal (F) over an entire period of the drive-controlling signals so as to make a peak value of the triangular wave constant, thereby adjusting the waveform of current flowing in the high-pressure discharge lamp.

Discharge lamp lighting device and system comprising it

An LCD projector (K ) comprising: a power source ( ); an image data source ( ) for producing an image data; a light source ( ) which is able to provide different levels of power; an LCD panel ( ) for modifying a light ray from the light source ( ) in accordance with said image data to produce light rays of an image; a projecting lens ( ) for projecting the light rays from the LCD panel ( ) onto a screen ( ) through enlargement; a control circuit ( ) for controlling an output of the power source ( ) so as to selectively set an output power: and a correcting circuit ( ) for correcting an image data before being supplied to the LCD panel ( ) so as to compensate the disturbance of the white balance caused by the change of the power of the light source ( ).

LCD projector

A liquid crystal projector that has a plurality of light sources for providing light to a light crystal panel, which functions as an image forming unit in the projector. A plurality of light source driving power sources are connected to the plural light sources individually by means of a light source lighting control circuit. As the light source lighting control circuit, a delay circuit, a counter circuit, or a programmed microcomputer is used. By controlling the light source driving power sources, each one of the plural light sources lights up sequentially or alternately in time. The light emitted from the light sources is modulated by the liquid crystal panel to produce a light image, and the light image is projected through the projector lens.

Growing community of inventors

Nishinomiya, Japan

Toshiyuki Noguchi