`
`[19]
`5,880,892
`[11] Patent Number:
`United States Patent
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`[45] Date of Patent:
`Mar. 9, 1999
`Ohtake
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`U8005880892A
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`[54] VARIABLE FOCAL LENGTH LENS SYSTEM
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`Inventor: M0t0yuki Ohtake, Kawasaki, Japan
`[75]
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`[73] Assigneei NikOIl Corporation, TOkYO, Japan
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`[21] Appl. No.: 904,841
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`Flled:
`Aug. 1’ 1997
`[22]
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`[30]
`Foreign Application Priority Data
`Aug. 1, 1996
`[JP]
`Japan .................................... 8—219483
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`Nov. 6, 1996
`[JP]
`Japan .................................... 8—309973
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`
`
`[51]
`Int. Cl.6 ..................................................... G02B 15/14
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`
`
`[52] US. Cl.
`............................................. 359/683; 359/676
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`[58] Field of Search ..................................... 359/676, 683,
`359/686, 689
`
`
`
`[56]
`
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`
`
`References Cited
`
`
`
`
`
`
`US PATENT DOCUMENTS
`5,499,141
`3/1996 Ohtake .................................... 359/676
`
`
`
`
`
`5,630,181
`5/1997 Ohtake .....
`.. 359/676
`
`
`
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`
`
`9/1997 Ohtake ~~~~~~~~~
`~~ 359/676
`5,668,667
`
`
`
`
`
`
`11/1997 NiShiO 6t a1~
`-
`596919851
`359/676
`
`
`
`
`7/1998 Ohtake .................................... 359/676
`5,781,348
`
`
`
`
`Primary Examiner—Scott J. Sugarman
`
`
`
`
`Attorney, Agent, or Firm—Chapman & Cutler
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`
`
`
`ABSTRACT
`
`
`[57]
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`Avariable magnification optical system of reduced size and
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`increased zoom ratio is provided. According to one aspect,
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`a positive lens group having positive refractive power Which
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`is disposed closest
`to an object and an end lens group
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`disposed closest to an image are provided. When lens group
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`positions are changed so that the system changes from the
`Wide-angle state to the telephoto state,
`the positive lens
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`group and the end lens group move toward the object. In this
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`case’ a ratio 0f the movmg amount 0f the POSitive lens group
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`t9 that Of the Chat tehs grOhPhOm the Wthe'ahgte htateth a
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`given state satisfies a particular condition. A simplified
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`barrel structure results when a particular first supporting
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`element for supporting a first lens group Which moves along
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`an optical axis and a particular second supporting element
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`for supporting an end lens group located closer to an image
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`than the first lens group are provided. The second supporting
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`element moves integrally With the end lens group along the
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`optical aXis. The second supporting element transmits a
`rotational driving force applied thereto to the first supporting
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`element and moves along the optical axis in accordance with
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`the rotational driving force. The first supporting element
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`moves along the optical aXis in accordance With the rota-
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`tional driving force transmitted thereto via the second sup-
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`porting element.
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`23 Claims, 32 Drawing Sheets
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`G1 G2 G3 G4
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`G5 G6
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`APPL—1033/ Page 1 of 49
`Apple v. Corephotonics
`
`APPL-1033 / Page 1 of 49
`Apple v. Corephotonics
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`

`

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`US. Patent
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`Mar. 9, 1999
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`Sheet 1 0f 32
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`5,880,892
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`FIG. 1
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`G1 G2 G3 G4
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`G5 G6
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`APPL-1033/ Page 2 of 49
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`APPL-1033 / Page 2 of 49
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`US. Patent
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`Mar. 9, 1999
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`
`SheetZ 0f32
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`5,880,892
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`APPL-1033/ Page 3 of 49
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`APPL-1033 / Page 3 of 49
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`US. Patent
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`Mar. 9, 1999
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`Sheet 3 0f 32
`
`5,880,892
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`APPL-1033/ Page 4 of 49
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`APPL-1033 / Page 4 of 49
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`US. Patent
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`Mar. 9, 1999
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`Sheet 4 0f 32
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`5,880,892
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`APPL-1033/ Page 5 of 49
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`APPL-1033 / Page 5 of 49
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`US. Patent
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`
`
`Mar. 9, 1999
`
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`
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`Sheet 5 0f 32
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`5,880,892
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`APPL-1033 / Page 6 of 49
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`

`
`US. Patent
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`
`
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`Mar. 9, 1999
`
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`
`Sheet 6 0f 32
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`5,880,892
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`APPL-1033/ Page 7 of 49
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`APPL-1033 / Page 7 of 49
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`US. Patent
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`
`
`Mar. 9, 1999
`
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`Sheet 7 0f 32
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`5,880,892
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`APPL-1033 / Page 8 of 49
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`APPL-1033 / Page 9 of 49
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`

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`US. Patent
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`
`
`
`Mar. 9, 1999
`
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`Sheet 9 0f 32
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`APPL-1033 / Page 10 of 49
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`US. Patent
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`Mar. 9, 1999
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`Sheet 10 0f 32
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`5,880,892
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`APPL-1033/ Page 11 of 49
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`APPL-1033 / Page 11 of 49
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`US. Patent
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`Mar. 9, 1999
`
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`Sheet 11 0132
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`5,880,892
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`APPL-1033 / Page 12 of 49
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`US. Patent
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`Mar. 9, 1999
`
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`Sheet 12 0f 32
`
`5,880,892
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`APPL-1033/ Page 13 of 49
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`APPL-1033 / Page 13 of 49
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`

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`US. Patent
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`Mar. 9, 1999
`
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`
`Sheet 13 0f 32
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`5,880,892
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`APPL-1033/ Page 14 of 49
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`APPL-1033 / Page 14 of 49
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`US. Patent
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`Mar. 9, 1999
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`Sheet 14 0f 32
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`5,880,892
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`APPL-1033/ Page 15 of 49
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`APPL-1033 / Page 15 of 49
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`US. Patent
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`Mar. 9, 1999
`
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`Sheet 15 0f 32
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`5,880,892
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`APPL-1033/ Page 16 of 49
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`APPL-1033 / Page 16 of 49
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`US. Patent
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`Mar. 9, 1999
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`Sheet 16 0f 32
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`APPL-1033/ Page 17 of 49
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`APPL-1033 / Page 17 of 49
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`US. Patent
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`
`Mar. 9, 1999
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`Sheet 17 0f 32
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`5,880,892
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`APPL-1033/ Page 18 of 49
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`Mar. 9, 1999
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`Sheet 18 0f 32
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`5,880,892
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`APPL-1033/ Page 19 of 49
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`Sheet 19 0f 32
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`APPL-1033/ Page 20 of 49
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`Mar. 9, 1999
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`Sheet 20 0f 32
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`APPL-1033 / Page 21 of 49
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`US. Patent
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`Mar. 9, 1999
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`Sheet210f32
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`5,880,892
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`APPL-1033 / Page 22 of 49
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`Mar. 9, 1999
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`Sheet 22 0f 32
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`5,880,892
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`APPL-1033/ Page 23 of 49
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`APPL-1033 / Page 23 of 49
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`Mar. 9, 1999
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`Sheet 23 0f 32
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`5,880,892
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`FIG. 25
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`G1
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`G6
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`APPL-1033/ Page 24 of 49
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`APPL-1033 / Page 24 of 49
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`Mar. 9, 1999
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`Sheet24 0f32
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`5,880,892
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`APPL-1033/ Page 25 of 49
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`APPL-1033 / Page 25 of 49
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`APPL-1033 / Page 26 of 49
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`Mar. 9, 1999
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`Sheet 26 0f 32
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`5,880,892
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`FIG.30
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`864
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`APPL-1033/ Page 27 of 49
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`APPL-1033 / Page 27 of 49
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`Mar. 9, 1999
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`Sheet 27 0f 32
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`5,880,892
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`FIG. 31
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`(W)
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`APPL-1033/ Page 28 of 49
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`APPL-1033 / Page 28 of 49
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`Mar. 9, 1999
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`Sheet 28 0f 32
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`FIG.32
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`APPL-1033/ Page 29 of 49
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`APPL-1033 / Page 29 of 49
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`Mar. 9, 1999
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`Sheet 29 0f 32
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`5,880,892
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`PRIOR ART
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`FIG. 34
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`APPL-1033/ Page 30 of 49
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`APPL-1033 / Page 30 of 49
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`Mar. 9, 1999
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`Sheet 30 0f 32
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`5,880,892
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`FIG. 35
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`PRIOR ART
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`APPL-1033/ Page 31 of 49
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`APPL-1033 / Page 31 of 49
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`Sheet 31 0f 32
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`5,880,892
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`APPL-1033/ Page 32 of 49
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`APPL-1033 / Page 32 of 49
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`Mar. 9, 1999
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`Sheet 32 0f 32
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`FIG. 37
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`PRIOR ART
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`APPL-1033/ Page 33 of 49
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`APPL-1033 / Page 33 of 49
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`5,880,892
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`2
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`invention, a
`According to one aspect of the present
`
`
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`
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`variable magnification optical system includes a positive
`
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`lens group G1, having positive refractive power and dis-
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`posed closest to an object, and an end lens group Ge which
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`is disposed closest to an image. The positive lens group G1
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`and the end lens group Ge are moved toward the object when
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`a state of lens group positions is changed from a wide-angle
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`state to a telephoto state. The following condition is always
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`satisfied when the state of lens group positions is changed
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`from a wide-angle state to a given state:
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`1
`VARIABLE FOCAL LENGTH LENS SYSTEM
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`
`BACKGROUND OF THE INVENTION
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`1. Field of the Invention
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`The present invention relates to a zoom lens system and,
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`in particular, relates to a zoom lens system including three
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`or more movable lens groups. The invention also relates to
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`a lens-barrel structure for a zoom lens system including
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`multiple lens groups.
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`2. Description of Related Art
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`It has recently become common to use a zoom lens in a
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`phototaking optical system used for a camera. In particular,
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`a camera including a high zoom ratio zoom lens having a
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`zoom ratio of more than three is now typical. Moreover, for
`a lens shutter type camera and an electric still camera,
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`various zoom lenses suitable for reducing sizes and increas-
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`ing zoom ratios are proposed, since small-sized lightweight
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`cameras are easily portable.
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`As such a high zoom ratio lens, a zoom lens configured so
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`that three or more lens groups are moved when the focal
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`length is changed, is typically used. This type of zoom lens
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`is referred to as a multi-group zoom lens. There have been
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`various proposals for multi-group zoom lenses.
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`In a multi-group zoom lens, there is an increased number
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`of spaces between the lens groups which can be changed
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`when the magnification changes, resulting in a complicated
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`lens-barrel structure. Various proposals related to a lens-
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`barrel structure suitable for a multi-group zoom lens or to a
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`lens-barrel structure suitable for reducing the size of the
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`main body of the camera have been made.
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`A phototaking optical system has a total lens length that
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`becomes longer as the zoom ratio increases. In order to
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`realize a reduction in size of the main body of the camera,
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`is necessary to make the phototaking optical system
`it
`thinner so that it may be accommodated in the main body of
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`the camera when the camera is carried. For example, it is
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`known to provide a two-stage barrel accommodating struc-
`ture in which the lens barrel is divided into two blocks and
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`is accommodated as if the lens barrel is folded.
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`However, in order to increase the zoom ratio of a zoom
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`lens in which a few of the lens groups are movable, a change
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`in lateral magnification of each lens group associated with
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`the magnification change becomes large. Therefore,
`it is
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`essential
`to control
`the lens group positions with high
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`accuracy in order to obtain a desired optical performance
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`when manufacturing the zoom lens, and it is difficult to
`shorten the total lens length of the zoom lens.
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`Furthermore, in a conventional zoom lens, a ratio of the
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`back focal length to the total lens length is large in the
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`telephoto state. Thus, it is easy for a lens-barrel to fall down
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`in the telephoto state, resulting in tilt of an image of an
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`object. This causes the image of the object to be partially
`blurred.
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`Additionally, when the number of movable lens groups is
`increased, the number of movable portions in the lens-barrel
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`is also increased. This causes a degraded optical perfor-
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`mance due to fatigue of the movable portions.
`SUMMARY OF THE INVENTION
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`The present invention is made in view of the aforemen-
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`tioned problems and has as one object the provision of a
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`variable focal length optical system or a variable magnifi-
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`cation optical system suitable for reducing the size and
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`increasing the zoom ratio of the system.
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`It is also an object of the present invention to provide such
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`a variable magnification optical system without a compli-
`cated lens-barrel structure.
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`10
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`0.3<|AGe/AG1|<0.6
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`where AG1 and AGe are moving amounts of the positive lens
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`group G1 and the end lens group Ge when the state of lens
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`groups is changed from the wide-angle state to the given
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`state, respectively.
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`In one preferred embodiment of the present invention, the
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`end lens group Ge has negative refractive power. The optical
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`system further includes a negative lens group Gn having
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`negative refractive power which is disposed adjacent to the
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`object-side of the end lens group Ge. In this case, it is
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`preferable to increase the space between the negative lens
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`group Gn and the end lens group Gn when the state of lens
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`group positions is changed from the wide-angle state to the
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`telephoto state.
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`In one preferred embodiment of the present invention, the
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`following condition is satisfied.
`0.8<f1/(fw-ft)1/2<1 .4
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`Here, fl is the focal length of the positive lens group G1, fw
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`is the focal length of the variable magnification optical
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`system in the maximum wide-angle state, and ft is the focal
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`length of the variable magnification optical system in the
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`telephoto state. Furthermore, it is preferable that the total
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`lens length TLt and the back focal length Bft in the telephoto
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`state satisfy the following condition.
`Bft/TLt<0.5
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`According to another aspect of the present invention, the
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`optical system includes a first lens group G1 and an end lens
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`group Ge located closer to an image than the first lens group
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`G1. Afirst supporting means supports the first lens group G1
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`which moves integrally with the first lens group along an
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`optical aXis, and a second supporting means supports the end
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`lens group Ge which moves integrally with the end lens
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`group Ge along the optical aXis. The second supporting
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`means transmits a rotation driving force applied thereto to
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`the first supporting means and moves along the optical aXis
`in accordance with the rotation driving force. The first
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`supporting means moves along the optical aXis in accor-
`dance with the rotation driving force transmitted via the
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`second supporting means.
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`In one embodiment, the first lens group G1 is disposed
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`closest to an object in the variable magnification optical
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`system and has positive refractive power. It is preferable to
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`dispose the end lens group Ge closest to the image in the
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`variable magnification optical system. A plurality of lens
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`groups is disposed between the first lens group G1 and the
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`end lens group Ge. A negative lens group Gn having
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`negative refractive power is provided adjacent to the object
`side of the end lens group Ge.
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`The second supporting means includes a first portion
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`which moves along the optical aXis while rotating in accor-
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`dance with a rotation driving force. A second portion of the
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`second supporting means moves along the optical aXis
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`without rotating in accordance with the rotation driving
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`force. The end lens group Ge is supported by the second
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`portion.
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`APPL-1033/ Page 34 of 49
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`APPL-1033 / Page 34 of 49
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`It is preferable for the second supporting means to include
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`a guide means for guiding the negative lens group Gn along
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`the optical aXis. Aratio of the moving amount of the negative
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`lens group Gn to that of the second supporting means varies
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`when a state of the lens group positions is changed from a
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`wide-angle state to a telephoto state.
`BRIEF DESCRIPTION OF THE DRAWINGS
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`FIG. 1 is a diagram showing a distribution of refractive
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`power in a variable magnification optical system according
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`to one embodiment of the present invention and represents
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`a change in state of lens group positions from the wide-angle
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`state (W) to the telephoto state (T).
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`FIG. 2 is a view schematically showing the configuration
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`of the variable magnification optical system according to the
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`embodiment of the present invention shown in FIG. 1.
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`FIGS. 3A—3D are graphs showing various aberrations in
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`the wide-angle state when the optical system is focused at
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`infinity.
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`FIGS. 4A—4D are graphs showing various aberrations in
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`the first intermediate focal length state when the optical
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`system is focused at infinity.
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`FIGS. 5A—5D are graphs showing various aberrations in
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`the second intermediate focal length state when the optical
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`system is focused at infinity.
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`FIGS. 6A—6D are graphs showing various aberrations in
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`the telephoto state.
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`FIGS. 7A—7D are graphs showing various aberrations in
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`the wide-angle state with an imaging magnification of —1/30.
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`FIGS. 8A—8D are graphs showing various aberrations in
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`the first intermediate focal length state with an imaging
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`magnification of —1/30.
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`FIGS. 9A—9D are graphs showing various aberrations in
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`the second intermediate focal length state with an imaging
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`magnification of —1/30.
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`FIGS. 10A—10D are graphs showing various aberrations
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`in the telephoto state with an imaging magnification of
`—1/30.
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`FIGS. 11A and 11B are cross-sectional views illustrating
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`a lens-barrel incorporating the variable magnification optical
`system of FIG. 2 and in which FIG. 11A illustrates the
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`lens-barrel in its wide-angle state and FIG. 11B illustrates
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`the lens-barrel in its telephoto state.
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`FIG. 12 is a diagram showing a distribution of refractive
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`power in a variable magnification optical system according
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`to another embodiment of the present invention and repre-
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`sents a change in state of lens group positions from the
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`wide-angle state (W) to the telephoto state (T).
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`FIG. 13 is a view schematically showing the configuration
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`of the variable magnification optical system according to the
`embodiment of the present invention shown in FIG. 12.
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`FIGS. 14A—14D are graphs showing various aberrations
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`in the wide-angle ate when the optical system is focused at
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`infinity.
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`FIGS. 15A—15D are graphs showing various aberrations
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`in the intermediate focal
`length state when the optical
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`system is focused at infinity.
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`FIGS. 16A—16D are graphs showing various aberrations
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`in the telephoto state when the optical system is focused at
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`infinity.
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`FIGS. 17A—17D are graphs showing various aberrations
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`in the wide-angle state with an imaging magnification of
`—1/40.
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`FIGS. ISA—18D are graphs showing various aberrations
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`in the intermediate focal
`length state with an imaging
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`magnification of —1/40.
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`10
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`15
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`25
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`30
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`35
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`4
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`FIGS. 19A—19D are graphs showing various aberrations
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`in the telephoto state with an imaging magnification of
`—1/40.
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`FIGS. 20A and 20B are cross-sectional views illustrating
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`a lens-barrel incorporating the variable magnification optical
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`system of FIG. 13 and in which FIG. 20A illustrates the
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`lens-barrel in its wide-angle state and FIG. 20B illustrates
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`the lens-barrel in its telephoto state.
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`FIG. 21 is a cross-sectional view illustrating the configu-
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`ration of the lens-barrel having a two-stage accommodating
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`structure in a variable magnification optical system accord-
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`ing to an embodiment of the present invention.
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`FIG. 22 is a view of the variable magnification optical
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`system and the lens-barrel shown in FIG. 21 as seen from the
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`image-side thereof (from the right-side in FIG. 21) along the
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`optical aXis.
`FIG. 23 is a cross-sectional view similar to FIG. 21 and
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`illustrates the variable magnification optical system and the
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`lens-barrel in wide-angle state.
`FIG. 24 is a cross-sectional view similar to FIG. 21 and
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`illustrates the variable magnification optical system and the
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`lens-barrel in the telephoto state.
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`FIG. 25 is a diagram showing a distribution of refractive
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`power in the variable magnification optical system accord-
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`ing to the embodiment of the present invention shown in
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`FIG. 21 and illustrates a manner in which the respective lens
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`groups move when a lens group position state is changed
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`from the wide-angle state (W) to the elephoto state (T).
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`FIG. 26 is a view showing the lens arrangement in the
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`variable magnification optical system according to the
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`embodiment of the present invention shown in FIG. 21.
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`FIG. 27 is a cross-sectional view illustrating the configu-
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`ration of the lens-barrel having a two-stage accommodating
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`structure in a variable magnification optical system accord-
`ing to another embodiment of the present invention.
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`FIG. 28 is a view of the variable magnification optical
`system and the lens-barrel shown in FIG. 27 as seen from the
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`image-side thereof (from the right-side in FIG. 27) along the
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`optical aXis.
`FIG. 29 is a cross-sectional view similar to FIG. 27 and
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`illustrates the variable magnification optical system and the
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`lens-barrel in he wide-angle state.
`FIG. 30 is a cross-sectional view similar to FIG. 27 and
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`illustrates the variable magnification optical system and the
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`lens-barrel in the telephoto state.
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`FIG. 31 is a diagram showing a distribution of refractive
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`power in the variable magnification optical system accord-
`ing to the embodiment of the present invention shown in
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`FIG. 27 and illustrates a manner in which the respective lens
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`groups move when a lens group position state is changed
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`from the wide-angle state (W) to the telephoto state (T).
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`FIG. 32 is a view showing the lens arrangement in the
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`variable magnification optical system according to the
`embodiment of the present invention shown in FIG. 27.
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`FIG. 33 is a cross-sectional view illustrating a conven-
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`tional lens-barrel having a two-state barrel accommodating
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`structure for a five-group zoom lens including, in order, a
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`positive lens group, a negative lens group, a positive lens
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`group, a positive lens group and a negative lens group.
`FIG. 34 is a view of the zoom lens and the lens-barrel
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`shown in FIG. 33 as seen from the image-side thereof (the
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`right-side in FIG. 33) along the optical aXis.
`FIG. 35 is a cross-sectional view similar to FIG. 33 and
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`illustrates the zoom lens and the lens-barrel in the wide-
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`angle state.
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`APPL-1033/ Page 35 of 49
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`APPL-1033 / Page 35 of 49
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`

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`5,880,892
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`FIG. 36 is a cross-sectional view similar to FIG. 33 and
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`illustrates the zoom lens and the lens-barrel in the telephoto
`state.
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`FIG. 37 is a view showing the shape of zoom cams (cam
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`grooves) formed within the second lens-barrel of FIG. 33.
`DESCRIPTION OF THE PREFERRED
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`EMBODIMENTS
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`A lens-integrated camera, such as a camera of a lens
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`shutter type which incorporates an imaging lens system in a
`main body of the camera, has no limitation to the back focal
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`length of the imaging lens system. Therefore, as the imaging
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`lens system used for such a camera, a telephoto-type zoom
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`lens, in which a negative lens group is disposed closest to an
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`image, is used.
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`Atelephoto-type zoom lens uses a negative lens group for
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`increasing the zoom ratio when the state of lens group
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`positions of the zoom lens is changed from a wide-angle
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`state (a state providing the shortest focal length of the zoom
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`lens) to a telephoto state (a state providing the longest focal
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`length of the zoom lens). The magnitude of the lateral
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`magnification of the negative lens group is larger in the
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`telephoto state than in the wide-angle state.
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`An aperture diaphragm is disposed closer to an object
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`than the negative lens group. The space between the aperture
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`diaphragm and the negative lens group is made narrower
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`when the state of lens group positions in the zoom lens is
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`changed from the wide-angle state to the telephoto state.
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`Therefore, off-axis light flux passes through the negative
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`lens group away from an optical axis of the zoom lens in the
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`wide-angle state. On the other hand, in the telephoto state,
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