ILLUMINATING DEVICE AND IMAGE PROJECTION DEVICE

PROBLEM TO BE SOLVED: To reduce the variation of light emitted from a light source and to restrain service life of the light source from getting short. SOLUTION: Turning on/off LEDs 31 and 33 is switched alternately. The illuminating device is provided with a liquid crystal switch capable of selecti...

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Bibliographische Detailangaben
1. Verfasser:	SUGIMOTO HISAYA
Format:	Patent
Sprache:	eng
Schlagworte:	ACCESSORIES THEREFOR APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USINGWAVES OTHER THAN OPTICAL WAVES APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FORPROJECTING OR VIEWING THEM CINEMATOGRAPHY DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING ELECTROGRAPHY FREQUENCY-CHANGING HOLOGRAPHY NON-LINEAR OPTICS OPTICAL ANALOGUE/DIGITAL CONVERTERS OPTICAL LOGIC ELEMENTS OPTICS PHOTOGRAPHY PHYSICS TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF
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Beschreibung
Zusammenfassung:	PROBLEM TO BE SOLVED: To reduce the variation of light emitted from a light source and to restrain service life of the light source from getting short. SOLUTION: Turning on/off LEDs 31 and 33 is switched alternately. The illuminating device is provided with a liquid crystal switch capable of selectively changing the polarized state of the light emitted from the LEDs 31 and 33 linked with switching timing of light emission by the LEDs 31 and 33. A current to be supplied to the LEDs 31 and 33 is controlled so that the quantity of light transmitted through the liquid crystal switch can be stabilized. The current supplied to the LEDs 33 and 31 is sampled (b1, b2,..., a8, a9) in a period extending over before and after the switching timing of the light emission by the LEDs 31 and 33. Indexes related to the variation of the current supplied to the LEDs 31 and 33 are derived from the sampled current values respectively and compared. On the basis of a result of comparison, timing to change the polarized light modulation state of the liquid crystal switch is adjusted. COPYRIGHT: (C)2008,JPO&INPIT