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:
Dec. 20, 1983
Filed:
Sep. 26, 1980
Isao Matsumura, Yokosuka, JP;
Yasuyuki Ishikawa, Kawaguchi, JP;
Reiji Hirano, Yokohama, JP;
Shigeo Maruyama, Machida, JP;
Yoshimi Kohayakawa, Yokohama, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
An eye-refractometer includes an objective optic having a first optical path, an apertured mirror for dividing the first optical path into a second optical path and a third optical path, a mask disposed in the second optical path and having linear marks orientated in at least three directions, a radiation source for illuminating the mask, a mask disposed in the third optical path and having liner detecting areas orientated in at least three directions and photocells arranged behind the respective areas. Improvements in this eye-refractometer comprise an apertured plate disposed between the apertured mirror and one of above said masks and an annular apertured plate disposed between said apertured mirror and the other mask. Another improvement is found in that the length of the linear detecting area is shorter than the length of optimum focused images of the linear marks.