Invention Grant
- Patent Title: Zoom lens and information device
- Patent Title (中): 变焦镜头和信息设备
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Application No.: US12828648Application Date: 2010-07-01
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Publication No.: US08179610B2Publication Date: 2012-05-15
- Inventor: Yohei Takano , Hiromichi Atsuumi
- Applicant: Yohei Takano , Hiromichi Atsuumi
- Applicant Address: JP Tokyo
- Assignee: Ricoh Company, Ltd.
- Current Assignee: Ricoh Company, Ltd.
- Current Assignee Address: JP Tokyo
- Agency: Oblon, Spivak, McClelland, Maier & Neustadt, L.L.P.
- Priority: JP2009-160297 20090706; JP2009-160299 20090706; JP2009-209864 20090910
- Main IPC: G02B15/14
- IPC: G02B15/14 ; H04N5/225

Abstract:
A zoom lens includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, which are disposed in order from an object side, and an aperture stop disposed at an object side of the third lens group. When changing the magnification from a wide angle end to a telephoto end, an interval between the first and second lens groups increases, an interval between the second and third lens groups decreases, and an interval between the third and fourth lens groups increases. The first lens group includes a negative lens, a positive lens, and a positive lens, in order from the object side. Predetermined conditions of a refractive index of the negative lens E1 for a d line, an Abbe number for d line, and a relative partial dispersion are satisfied.
Public/Granted literature
- US20110002048A1 ZOOM LENS AND INFORMATION DEVICE Public/Granted day:2011-01-06
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