PROJECTION OPTICAL UNIT, PROJECTION TYPE COLOR VIDEO DISPLAY DEVICE, AND BACK PROJECTION TYPE COLOR VIDEO DISPLAY DEVICE USING PROJECTION OPTICAL UNIT

摘要

PPROBLEM TO BE SOLVED: To make the compaction of a set compatible with high focus by drastically shortening a projection distance of a projection optical unit in a projection type color video display device and a back projection type color video display device. PSOLUTION: In the case of a projection lens device having two lens groups, a 1st magnified image (magnification M1) formed by the 1st lens group (22) arranged most proximately to a video display element is temporarily formed on a side nearer to the video display element than to the 2nd lens group (24). The 1st enlarged image is enlarged and projected (magnification M2, provided that M2M1) to a screen by the 2nd lens group. A field lens group (23) having positive refractive power is arranged between the 1st and the 2nd lens groups. As a result, a relation between F2 being the F value of the 2nd lens group and F1 being the F value of the 1st lens group becomes F2=F1/M1, so that a super wide angle whose viewing angle exceeds 90 degrees is realized. PCOPYRIGHT: (C)2005,JPO&NCIPI