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Patent US4952962A successfully refreshed from Google Patents.
US4952962A
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US
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Automatic focusing device
Assignee: Pentax Corp
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Filing: 1989-06-09
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Granted: 1990-08-28
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Expires: 2009-06-09
Abstract
Abstract Disclosed herein is an automatic focusing device high in focusing accuracy, in which an amount of drive for driving a focusing lens to a position focused on an object can be renewed during the focusing lens moving to the focused position. Further, the automatic focusing device is provided with a speed changing means capable of changing the movement speed of the focusing lens according to an amount of drive to the focused position.
Inventors
- 👤 Noboru Suzuki
- 👤 Shigeo Tohji
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:31
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/36
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
107 words
An automatic focusing device comprising: a lens system including a focusing lens; means for driving said focusing lens; a first means for calculating an amount of defocusing for an object; a second means for calculating an amount of drive for moving said focusing lens to a position focused to said object based on the amount of defocusing; and a third means for controlling said driving means to gradually vary the movement speed of said focusing lens according to the amount of drive obtained by said second means said driving means moving said focusing lens to the focused position at the movement speed controlled by said third means.
Claim 2
Dependent Claim
107 words
An automatic focusing device comprising: a lens system including a focusing lens; means for driving said focusing lens; a first means for calculating an amount of defocusing for an object; a second means for calculating an amount of drive for moving said focusing lens to a position focused to said object based on the amount of defocusing; and a third means for controlling said driving means to gradually vary the movement speed of said focusing lens according to the amount of drive obtained by said second means said driving means moving said focusing lens to the focused position at the movement speed controlled by said third means.
Claim 3
Dependent Claim
34 words
The device as defined in claim 1 wherein said second means calculates the amount of drive P according to ##EQU2## where K is lens movement conversion coefficient and D is the amount of defocusing.
Claim 4
Dependent Claim
26 words
The device as defined in claim 2 wherein the coefficient K is a constant which has been stored in a lens ROM of said lens system.
Claim 5
Dependent Claim
51 words
The device as defined in claim 1 further comprising a fourth means for detecting brightness of the object, said third means controlling said driving means to vary the movement speed of said focusing lens according to the amount of drive and the brightness of the object detected by said fourth means.
Claim 6
Dependent Claim
56 words
The device as defined in claim 1 further comprising a fifth means for comparing the amount of drive detected by said second means with a reference value, said third means controlling said driving means to vary the movement speed of said focusing lens according to the amount of drive and an output of said fifth means.
Claim 7
Dependent Claim
35 words
The device as defined in claim 1 wherein the control of the movement speed is carried out by driving said driving means in either a DC control mode or a pulse width modulation control mode.
Claim 8
Dependent Claim
102 words
The device as defined in claim 1, further comprising a sixth means for calculating the difference between the amount of drive detected by said second means and the total pulse count value corresponding to the amount said drive means has driven said focusing lens, said difference being compared with a plurality of stored reference values of decreasing magnitudes, wherein the movement speed of the lens is reduced as said difference becomes smaller than said reference values until the amount of drive detected by said second means equals the total pulse count value, at which time said third means stops said driving means.
Claim 9
Dependent Claim
83 words
The device as defined in claim 1, further comprising seventh means for calculating start pulse data corresponding to voltage and temperature variations of the driving means and eighth means for calculating the total pulse count value corresponding to the amount said drive means has driven said focusing lens, wherein when the amount of drive detected by said second means is below a predetermined value, said driving means drives said lens until said total pulse count value is greater than said start pulse data.
Claim 10
Dependent Claim
93 words
The device as defined in claim 8, further comprising ninth means for calculating the difference between the amount of drive detected by said second means and said total pulse count value detected by said eighth means, said difference being compared with a plurality of reference values of decreasing magnitudes, wherein the movement speed of the lens is reduced as said difference becomes smaller than said reference values until the amount of drive detected by said second means equals the total pulse count value, at which time said third means stops said driving means.
Claim 11
Dependent Claim
23 words
The device as defined in claim 1, wherein said first means calculates the direction of defocusing, as well as the amount of defocusing.
Claim 12
Dependent Claim
77 words
The device as defined in claim 1, wherein said third means comprises a memory for storing a plurality of duty ratio values, corresponding to different drive amounts calculated by said second means, and means responsive to said second means for reading one of said duty ratio values out of said memory means, said driving means driving said focusing lens with drive pulses having a duty ratio corresponding to the duty ratio value read out of said memory.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-27 | 1994-02-26 | 1994-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-27 | 1998-02-26 | 1998-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-27 | 2002-02-26 | 2002-08-28 | $7700.00 | Window Closed / Lapsed |