The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 25, 2008
Filed:
Jan. 03, 2007
Hidehiro Ikeda, Yokohama, JP;
Shuji Kato, Yokohama, JP;
Koji Hirata, Yokohama, JP;
Naoyuki Ogura, Machida, JP;
Hidehiro Ikeda, Yokohama, JP;
Shuji Kato, Yokohama, JP;
Koji Hirata, Yokohama, JP;
Naoyuki Ogura, Machida, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An inexpensive projection lens unit in a rear projection type image display system, having a short focal distance (wide angle of viewing field), high focus and high contrast, and as well, including a power lens made of a glass material having a high refractive index in a range from 1.63 to 1.70 and an Abbe's number of not less than 50 with an optimized incident and emergent configuration in order to satisfactorily correct aberration with a enhanced focusing performance even with a shortened focal distance. Further, the power lens having a high refractive index can exhibit a high power, and accordingly, can carry out satisfactory aberration correction by optimizing the aspheric degree of a plastic lens even though the length of back focus is increased for enhancing the contrast.