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:
May. 19, 2009
Filed:
Nov. 03, 2006
Hiroki Yoshikawa, Hiratsuka, JP;
Takanori Hisada, Yokohama, JP;
Tetsu Ohishi, Hiratsuka, JP;
Koji Hirata, Yokohama, JP;
Naoyuki Ogura, Machida, JP;
Hiroki Yoshikawa, Hiratsuka, JP;
Takanori Hisada, Yokohama, JP;
Tetsu Ohishi, Hiratsuka, JP;
Koji Hirata, Yokohama, JP;
Naoyuki Ogura, Machida, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An image that has been displayed on the display screen of an image generator is first passed through a projection lens section consisting of a front group and a rear group. Next after being reflected on the reflecting surface of a free-form surface mirror, the image is further reflected by a planar reflecting mirror and then obliquely projected from the lower section of a projection screen onto the screen. The front group of the projection lens section is provided for enlarging the image. In order to correct aberration due to oblique projection onto the projection screen, the rear group uses a free-form surface lens that forms a concave shape with respect to the exit side of light from the lens. The free-form surface mirror corrects trapezoidal distortion due to oblique projection onto the projection screen. The free-form surface lens in the rear group of the projection lens section can accommodate changes in environmental conditions by using one edge as a reference edge and rendering the other edge expandable. The free-form surface mirror can likewise use one edge as a reference edge and render the other edge expandable. For adjustment, the free-form surface mirror can also be pivoted about the reference edge.