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. 29, 2015
Filed:
Jan. 15, 2015
Takuya Nagano, Kanagawa, JP;
Takuya Nagano, Kanagawa, JP;
RICOH COMPANY, LTD., Tokyo, JP;
Abstract
An image reading lens includes a front lens group of five lenses including a positive lens and a negative lens, disposed on an object side and a rear lens group disposed on an image side, including a negative plastic lens. The image reading lens satisfies the following conditions:0<Σ()−Σ()<250.10<<0.90−1.5<<−0.50.35<<0.70where Σdn/dt(N) and Σdn/dt(P) are sums of 10-fold temperature coefficients of refractive indexes of the negative and positive lenses of the front lens group along a He—Ne line at a temperature of 40 to 60° C., respectively, fa, fb, and f are focal lengths of the front lens group, rear lens group, and image reading lens, respectively, dis an on-axis distance between the front and rear lens groups, and D is the total length of the image reading lens.