Patent US5233472A successfully refreshed from Google Patents.
US5233472A
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US
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Method of controlling a zoom lens assembly
Assignee: Pentax Corp
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Filing: 1992-05-19
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Granted: 1993-08-03
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Expires: 2012-05-19
Abstract
Abstract A method of controlling the focusing of a zoom lens which has a plurality of lens groups including at least one focusing lens group, wherein an amount of deviation from focus caused by a zooming operation is corrected by movement of the focusing lens group. The method includes setting a reference object distance, at which no deviation from focus occurs during zooming of the zoom lens, at a finite object distance, such that the amount of movement of the focusing lens group necessary to effect focusing is determined based upon a reference position corresponding to a position of the focusing lens group at the reference object distance, in accordance with focal length data and object distance data.
Inventors
- 👤 Keisuke Haraguchi
- 👤 Yukio Takaoka
- 👤 Takayuki Ito
- 👤 Tomoaki Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 17:24
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/02; G02B7/04; G02B7/10; G02B7/102; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
53 words
A method of focusing a zoom lens in which said zoom lens includes a plurality of movable lens groups, including a movable focusing lens group, said method comprising positioning said focusing lens group at a finite reference position determined by photographic data and the respective positions of said plurality of movable lens groups.
Claim 2
Independent Claim
53 words
A method of focusing a zoom lens in which said zoom lens includes a plurality of movable lens groups, including a movable focusing lens group, said method comprising positioning said focusing lens group at a finite reference position determined by photographic data and the respective positions of said plurality of movable lens groups.
Claim 3
Dependent Claim
32 words
A method of focusing a zoom lens according to claim 1, wherein said finite reference position is a position at which no deviation from focus occurs during zooming of said zoom lens.
Claim 4
Dependent Claim
35 words
A method of focusing a zoom lens according to claim 1, further comprising: displacing said movable focusing lens group, after zooming of said zoom lens, to correct a displacement of focus caused by said zooming.
Claim 5
Dependent Claim
37 words
A method of focusing a zoom lens according to claim 1, wherein said finite reference position is approximately 1.5 to 2.5 times the closest object distance at which an object can be focused by said zoom lens.
Claim 6
Dependent Claim
35 words
A method of focusing a zoom lens according to claim 4, wherein said finite reference position is approximately 2 times the closest object distance at which an object can be focused by said zoom lens.
Claim 7
Dependent Claim
51 words
A method of focusing a zoom lens according to claim 1, further comprising: measuring object distance by means of an object distance measuring device; and determining said finite reference position to be approximately 1.5 to 2.5 times the furthest object distance which said object distance measuring device is capable of measuring.
Claim 8
Dependent Claim
37 words
A method of focusing a zoom lens according to claim 6, wherein said finite reference position is determined to be approximately 2 times the furthest object distance which said object distance measuring device is capable of measuring.
Claim 9
Dependent Claim
41 words
A method of focusing a zoom lens according to claim 1, wherein positioning said focusing lens group at said finite reference position is further determined by taking into account an object distance where focusing precision is desired to be most accurate.
Claim 10
Dependent Claim
38 words
A method of focusing a zoom lens according to claim 1, wherein said zoom lens comprises first and second lens groups, further comprising: focusing said zoom lens by moving a lens group other than said first lens group.
Claim 11
Dependent Claim
44 words
A method of focusing a zoom lens according to claim 1, wherein said zoom lens comprises first, second and third lens groups, said method further comprising: focusing said zoom lens by moving a part of a lens group other than said first lens group.
Claim 12
Dependent Claim
40 words
A method of focusing a zoom lens according to claim 1, wherein said zoom lens comprises first, second and third lens groups, said method further comprising: focusing said zoom lens by moving a plurality of said lens groups in unison.
Claim 13
Dependent Claim
39 words
A method of focusing a zoom lens according to claim 1, wherein said zoom lens comprises first, second and third lens groups, said method further comprising: focusing said zoom lens by moving a plurality of said lens groups separately.
Claim 14
Dependent Claim
58 words
A method of focusing a zoom lens according to claim 1, wherein said focusing lens group includes a plurality of lens groups, said method further comprising: moving said plurality of lens groups of said focusing lens group in unison to effect zooming; and moving said plurality of lens groups of said focusing lens group separately to effect focusing.
Claim 15
Dependent Claim
57 words
A method of focusing a zoom lens according to claim 1, wherein said focusing lens group includes a plurality of lens groups, said method further comprising: moving said plurality of lens groups of said focusing lens group separately to effect zooming; and moving said plurality of lens groups of said focusing lens group separately to effect focusing.
Claim 16
Dependent Claim
83 words
A method of focusing a zoom lens according to claim 1, wherein said zoom lens comprises first, second and third lens groups, said method further comprising: focusing said zoom lens by moving said second and third lens groups separately, and wherein said focusing lens group comprises lenses having focal length ranges and lens powers which effect displacements of said focusing lens group on a sorter focal length side substantially equal to displacements of said focusing lens group on a longer focal length side.
Claim 17
Dependent Claim
53 words
A method of focusing a zoom lens according to claim 1, wherein said zoom lens comprises first, second and third lens groups, and said second lens group includes two sub-groups, said method further comprising: independently moving said sub-groups to effect zooming; and focusing said zoom lens by moving said sub-groups as a unit.
Claim 18
Dependent Claim
52 words
A method of focusing a zoom lens according to claim 1, wherein said zoom lens comprises first, second and third lens groups, and said second lens group includes two sub-groups, said method further comprising: independently moving said sub-groups to effect zooming; and focusing said zoom lens by moving said third lens group.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1996-08-02 | 1997-02-01 | 1997-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-02 | 2001-02-01 | 2001-08-03 | $3760.00 | Window Closed / Lapsed |
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