U.S. patents available from 1976 to present.
U.S. patent applications available from 2005 to present.

Small-sized real image mode zoom finder

Patent 6084720 Issued on July 4, 2000. Estimated Expiration Date: Icon_subject October 27, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Patent References

Keplerian variable magnification finder Patent #: 5920427
Issued on: 07/06/1999
Inventor: Ogata

Inventor

Assignee

Application

No. 179320 filed on 10/27/1998

US Classes:

359/676, With variable magnification (e.g., zoom type)359/422, Variable magnification359/432, Variable magnification359/686, Four groups396/379, Zoom396/382Lens detail

Examiners

Primary: Epps, Georgia
Assistant: Spector, David N.

Attorney, Agent or Firm

Foreign Patent References

  • 5-164964 JP. 06/12/1993
  • 7-128707 JP. 05/12/1995
  • 8-240769 JP. 09/12/1996
  • 10-123590 JP. 05/12/1998

International Classes

G02B 015/14
G02B 023/00
G03B 013/06
G03B 013/10

Foreign Application Priority Data

1997-10-28 JP

Abstract

A real image mode zoom finder includes, in order from the object side, an objective optical system with positive refracting power having a first lens unit with negative refracting power, a second lens unit with positive refracting power, a third lens unit with positive refracting power, and a fourth lens unit with negative refracting power; an image erecting system for erecting an intermediate image formed by the objective optical system; and an ocular optical system with positive refracting power. In this case, each of lens units constituting the objective optical system is constructed with a single lens, and the object-side surface of the first lens unit is configured to be concave. Moreover, the objective optical system satisfies the following condition:2.5<଱T(R2) <5.7where ଱T(R2) is a combined longitudinal magnification ranging from the second lens unit of the objective optical system to the intermediate image at the telephoto position of the finder.

PatentsPlus Images
Enhanced PDF formats
loading...
PatentsPlus: add to cart
PatentsPlus: add to cartSearch-enhanced full patent PDF image
$9.95more info
PatentsPlus: add to cart
PatentsPlus: add to cartIntelligent turbocharged patent PDFs with marked up images
$18.95more info
 
Sign InRegister
Username  
Password   
forgot password?